Journal of Agriculture Volume 109, No. 1, 2008 and … · and Rural Development in the Tropics and Subtropics Volume 109, ... 981313, EMail: [email protected] Editors ... Las

Journal of Agriculture

and Rural Development in

the Tropics and Subtropics

Volume 109, No. 1, 2008

Comparisons of Production Costs and Profit of

Three Different Technology Levels of

Papaya Production in Tabasco, Mexico

Plant Genetic Resources: Selected Issues

from Genetic Erosion to Genetic Engineering

Factors Influencing

Irrigation Technology Adoption and its

Impact on Household Poverty in Ghana

Vernacular Languages and Cultures in

Rural Development: Theoretical Discourse and

Some Examples

Interaction between Coffee (Coffea arabica L.)

and Intercropped Herbs under Field Conditions

in the Sierra Norte of Puebla, Mexico

Decomposition of Organic Substrates and

their Effect on Mungbean Growth in Two Soils

of the Mekong Delta

1

15

51

65

85

95

E. Guzman-Ramon, R. Gomez

Alvarez, H. A. J. Pohlan,

J. C. Alvarez-Rivero,

J. Pat-Fernandez and

V. Geissen

K. Hammer and Y. Teklu

Adetola I. Adeoti

E. Nercissians and M. Fremerey

A. Pacheco Bustos,

H. A. J. Pohlan and M. Schulz

M. Becker, F. Asch,

N. H. Chiem, D. V. Ni,

E. Saleh, K. V. Tanh and

T. K. Tinh

I

Journal of Agriculture and Rural Development in the Tropics and Subtropics

formerly:

Der Tropenlandwirt. Beitrage zur tropischen Landwirtschaft und Veterinarmedizin,

Journal of Agriculture in the Tropics and Subtropics

ISSN 1612-9830

Publisher

German Institute f. Tropical and Subtropical Agriculture (DITSL GmbH), Witzenhausen

Association for Sustainable Development (GNE mbH), Witzenhausen

Institute for tropical Agriculture e.V., Leipzig

University of Kassel, Faculty of Organic Agricultural Sciences, Witzenhausen

Association of Agronomists in the Tropics and Subtropics Witzenhausen, e. V., (VTW)

Executive Manager and Editor in Chief

Hans Hemann, Steinstraße 19, D 37213 Witzenhausen, Tel. 05542 - 981216,

Telefax 05542 - 981313, EMail: [email protected]

Editors

Prof. Dr. Schahram Banedjschafie Dr. Heinrich Lehmann - Danzinger

Prof. Dr. Eckhard Baum Prof. Dr. Jurgen Pohlan

Prof. Dr. Jorg Borgman Prof. Dr. Christian Richter

Dr. habil. Dr. h.c. W. Drauschke Dr. Sahle Tesfai

Dr. Jens Gebauer Prof. Dr. Eva Schlecht

Prof. Dr. Karl Hammer Dr. Florian Wichern

Prof. Dr. Oliver Hensel Prof. Dr. Peter Wolff

Dr. Christian Hulsebusch

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II


Volume 109, No. 1, 2008, pages 1–14

Comparisons of Production Costs and Profit of Three Different

Technology Levels of Papaya Production in Tabasco, Mexico

E. Guzman-Ramon ∗1, R. Gomez Alvarez 1, H. A. J. Pohlan 2, J. C. Alvarez-Rivero 3,

J. Pat-Fernandez 4 and V. Geissen 1

Abstract

The survey was carried out from September 2006 to January 2007 in three papaya

production sites located in main papaya production zones in Tabasco; SE Mexico. There

are differences in size of the cultivated area, in the yield of the papaya as well as in

production costs and profit, according to the different technology levels in the farming

systems: low, medium and high technology cultivation level. The financial evaluations

were carried out in three sites with different productive technologies. The comparison of

the agronomic and economic traits results for low technology level in: V AN of 2359.00

USD, BCR in 1.9 and an equilibrium point of 3750.00 USD, TIR of 0.25. In order to

avoid loses, a quantity of 10714 kg papaya should be sold. In medium technology V AN

is 1605.10 USD, BCR is 1.7, TIR 0.20 and the equilibrium point is 12800.00 USD.

36571 kg of papaya should be yearly sold. In high technology level V AN is 11749.40,

BCR is 2.73, TIR 0.43 and the equilibrium point is 12187.50 USD, 34821 kg papaya

should be sold yearly. The indicators showed that all three levels are profitable and

economically viable.

Keywords: investment, yield, production costs, benefit - cost - ratio, equilibrium point

Resumen

La investigacion se llevo a cabo en 3 unidades de produccion de papaya ubicadas en las

principales zonas agroecologicas productoras de papaya en el Estado de Tabasco entre

Septiembre 2006 a Enero de 2007. Existen diferencias en el tamano del area cultivada, en

rendimientos de la papaya ası como en costos de produccion y rentabilidad, de acuerdo

a las diferentes tecnologıas utilizadas en las unidades de produccion: alto, mediano y

bajo nivel de tecnificacion del proceso productivo). Las evaluaciones financieras fueron

realizadas en tres unidades de produccion ubicadas en Cunduacan, Teapa y Balancan.

La comparacion de los aspectos agronomicos y economicos resulto en tecnologıa baja:

V AN es de USD 2359.20; RB/C es 1.9 y el punto de equilibrio es de USD 3750.00 y

∗ corresponding author, email: [email protected] El Colegio de la Frontera Sur-Unidad Villahermosa, Tabasco, Mexico.2 Universitat Bonn, INRES, Auf dem Hugel 6, D-53121 Bonn, Germany. International Consultor3 Universidad Juarez Autonoma de Tabasco, Division de Ciencias Agropecuarias, Tabasco,

Mexico4 El Colegio de la Frontera Sur-Unidad Campeche, Mexico.

1

TIR es 0.25; para no tener perdidas se debe vender 10714 kg de papaya. En tecnologıa

media: V AN es de USD 1605.10; RB/C es 1.7, TIR 0.20 y el punto de equilibrio

que es de USD 12800.00 y 36571 kg. En tecnologıa alta: V AN es de USD 11749.40;

RB/C es 2.73, TIR 0.43 y el punto de equilibrio que es de USD 12187.50 y 34821 kg.

Los indicadores demostraron que todos los niveles son rentables.

Palabras clave: inversion, rendimiento, costos de produccion, beneficio-costo, punto de

equilibrio.

1 Introduction

Mexico is immersed in a deep changing process. Thousands of big agro exporting

enterprises are successful while an outstanding proportion of commercial producers are

in bankrupt. Small farms are impoverished; however they do not disappear due to the

lack of employment alternatives. It is necessary to rethink about the rural concept when

the agricultures produce only for self consumption without the possibility to develop their

market production subsisting on incomes gotten thanks to complex temporary migratory

processes. It is imperative for Mexican farmers to become managers taking advantage

on their experience and the needed implications for the organization of the production,

education, training, product organization, commerce transformation, supplying of own

personnel or use of technology (Pohlan et al., 2007; Plata, 2000). In a great number

of cases farmers in the tropics have the same social economical and financial problems,

such as the lack of technology, substructure for the production and commercialization,

training and technical assistance, organization to produce and commercialize in a proper

way, productive chain articulation, subsidies and lack of strategies to develop human

factor (Wander et al., 2007; Mendez Garrido, 2005, p.9).

Nation wide, Tabasco occupied the eighth position of Mexican papaya producers with

662 ha, with a total production of 214,679 tons per year (SAGARPA, 2005). Tabasco

has a humid tropical climate where the growth of papaya (Carica papaya L.) is propiti-

ated. Papaya cultivating areas have increased between 1991 (187 ha) and 2001 (2126

ha) (SAGARPA, 2001). During the last years papaya production has reached a rise in

sown land surface, the Maradol and Zapote varieties are the most commercialized species

at the moment with yields of more than 27 t ha−1 which has sustained as a profitable

product for the small farmers of the Centro and Chontalpa regions of Tabasco. For

most producers the Maradol variety is sown in an 80% and the rest are the varieties

Zapote and Tabasco 95. The main problem in fruit production is the presence of the

fruit annular rotting caused by a virus (Mirafuentes Hernandez, 2001). Because of

this, Tabasco is making an update of the producers’ census list with the support of their

districts and the integration of the product System State Council to organize producers

on the getting, post-harvest handling and commercialization of this papaya fruit. The

papaya production and commercialization is a challenge for each of the municipalities

in the state, due to structural and fundamental problems starting with the handling

of crops, the application of proper technology, infrastructure, training, technical assis-

tance, meteorological phenomena, pests and diseases until the aggregated value chains

and commercialization as well as the investment needed to get a greater income.

2

2 Methods and Materials

2.1 Study area

Tabasco is located in south east of Mexico; it extends from the Gulf of Mexico plain

coast to the north of Chiapas’ Sierra. Tabasco soils are mainly alluvial soils on flat

and lowlands, excepting for the limiting zone with Chiapas which is mountainous. The

climate is humid and hot distinguished by high temperatures quite uniform with an an-

nual mean of 26° C. There are three important papaya producing sub regions, Chontalpa,

Centro-Sierra and Los Rios, each one with different features. Most of the low technology

farmers are found in the Chontalpa and Centro sub regions, mainly in the municipali-

ties of Cunduacan, Huimanguillo and Cardenas, which represents the 88% of the total

shown land among 1-5 ha. The medium technology farmer are found in Cunduacan,

Huimanguillo and Teapa which represent 7.5 % of papaya area with plantations between

5 to 10 ha. The high technology farmers are located in Balancan representing only 4.5

% of the total, with plantations of more than 10 ha in size. According to the data of

SAGARPA (2005), in Tabasco are 189 Maradol papaya temporary producers (610 ha)

and 10 farmers with 33 ha irrigated papaya cropping. In Chontalpa the greatest number

of low technology producers (175 farmer) is concentrated with surfaces between 1 to 2

hectares (manual and temporary crops), 24 medium technology producers in Chontalpa

and Centro-Sierra. The high technology producers are located in Balancan, in Los Rios

region where there is a small number of producers and great areas of high technologies

(irrigation and mechanization) with sown areas between 10 and 40 ha. with a total of

199 producers (SAGARPA, 2006).

This study was carried out in six main papaya producing municipalities in Tabasco:

Huimanguillo, Cardenas, Cunduacan, Centro, Teapa and Balancan (Figure 1).

By stratified sampling, 67 surveys were applied in these 6 municipalities. For the data

analysis of the survey, the DYANE statistical software (Santesmases, 2005) was used.

For the economical analysis we determined the yields obtained in the field, carrying out

interviews with producers and own observation.

For each technology level (low, medium and high) we selected three production units to

be studied in their handling of the product and their costs/profits ratios.

For the comparison between the different technology levels were analyzed the following

economical indicators:

Net present value (V AN):

V AN = −p + (F1/(1 + i)1 + F2/(1 + I)2 + F3/(1 + i)3 + · · · + Fn/(1 + i)n

Benefit – cost – ratio (BCR):

BCR = profit/total costs

Point of equilibrium (PE):

PE = fixed costs/(1 − variable costs/net sales);

PE = TIR being V AN = 0

3

Discount rate (TIR):

TIR= by which the V AN is equal to zero, and it is defined as the I (its determined

by rough calculation) that is made with the discounted flows being equal to the initial

investment. Once the information was obtained, it was organized and systemized ac-

cording to the fix and variable costs, determining the total papaya production costs in

the three levels of technology to calculate the profitability product indicators at the price

in January 2006. The aspects analyzed were the fixed costs and the production costs,

in the papaya production process, during the first 12 months with a 5 year projection to

obtain financial indicators: net present value (V AN), benefit/cost ratio (RB/C), TIR

and point of equilibrium (PE).

The V AN is defined as the result of the difference between the updated incomes

(positive values) and updated costs (negative values) to a determinate discount rate

(Coss Bu, 2001, p. 61). This discount rate allows making comparable the flow either

incomes or costs. When the V AN is positive to a higher rate tax than 15% annual, it

is considered that the project profitability is acceptable and thus financially convenient.

Depreciation is the diminution of the price or value that suffers to a product as a con-

sequence of the use and time. It is only applied to the fix actives; all the enterprises

should base their calculations of their depreciations in the Financial Law (art. 37 of the

LISR). This is calculated only for medium and high technology levels.

The different technological papaya production levels were determined by the main fac-

tors such as cultivation density, crop size, use of irrigation, use of agrochemicals, agro

ecological handling, rank of crop significance, harvest method and post harvest handling

(Table 1). The main elements to differentiate the level of technology were the culti-

vating system and the use of materials and agricultural implements such as tractors,

irrigation system and transportation means.

Table 1: Papaya production technologies in Tabasco (classification based inSAGARPA (2005); Silva Torres (2002).

Technology levelConcept

Low Medium High

Crop density per ha 1100 plants 1600 plants 2200 plants

Size of plantation (ha) 1 to 4 5 to 10 10 or more

Use of irrigation no tubes or drops drops or tubes

Use of agrochemicals low medium high

Agro ecological handlings low low low

Productive Structure(Rank of crop importance)

10% or less withpapaya

30% of the area ispapaya

more than 50% ispapaya

Harvest method manual manual & with equipment with equipment

Post Harvest handling manual medium technician highly process technician

4

Figure 1: Sites of the papaya cultivation areas in Tabasco, Mexico.

Yield t ha -1 33.3Prod. (t) 2,684Soil: Gleysol

lowSITE 1

Technology lowSITE 6


Yield t ha -1 38.4Prod. (t) 24,550Soil: Gleysol andCambisol

highSITE 5

Yield t ha -1 37.8Prod. (t) 525Soil: Gleysol

mediumSITE 4


mediumSITE 3


mediumSITE 2

3 Situation of the papaya cultivation in Tabasco

The papaya production in Tabasco is mainly characterized economically and socially

of low production technology, for which is the main economical activity and its main

familiar source of income for the producers by selling their produce in the local and

national market by intermediaries. In contrast to them, the producers with medium and

high technologies have a high income potential in the national and international markets

due to the great demand of this fruit.

Based in the project carried out by Semillas del Caribe (2000), the production cost

per hectare of Maradol papaya, under average conditions in Mexico, and considering a

cycle of 18 months (2 months in nursery, 7 in crop growing and 9 in fructification and

harvest) it was determined in a total of $105,548.50 Mexican pesos, (1 USD≈$10.00Mexican pesos) with partial costs for tillage $3,190.00; $4,647.50 for the planting prepa-

ration, sowing $1,540.00; irrigation $3,400.00; weed control $3,100.00; pest manage-

ment $24,987.00; fertilization $26,244.00; cultivating handling $9,940.00 and harvest

$28,500.00 (Semillas del Caribe, 2000).

The price paid to the producer per kilogram of fruit in 1999 varied from $2.00 to $6.00(0.20 USD to 0.60 USD), depending on the fruit quality, the season and the market

to it was sent. In the year 2006 the price paid to the producer by the intermediary in

Tabasco was the same as 6 years ago.

Silva Torres (2002) reported that the average income obtained by the small producers

in a two year producing cycle is $181,260 pesos ha−1, harvesting 95.4 t ha−1 with a

price of 1.90 pesos ha−1 of fruit. In contrast, the medium producers have an average

5

income of $529,332 pesos ha−1, and the high technology producers have incomes of

$618,800 pesos ha−1 selling at 3.4 pesos ha−1 (Table 2).

Table 2: Comparison of production costs (Mexican pesos ha−1) in a 2 year cycle in SanPedro, Balancan (Silva Torres, 2002).

Concept Small holding farmers Medium size farmers Big size farmers

Land Acquisition 0 0 3750

Machinery and Equipments 6477 16179 50375

Land conditioning 2044 1368 4041

Nursery 5465 2565 1011

Transplanting 522 801 486

Irrigation 11435 4022 2231

Pest management 15315 31482 31131

Weed control 1258 3166 1697

Fertilization 6441 20139 34075

Cultivating labours 390 468 477

Harvest an post harvest 15743 19432 38549

Transport 0 64633 79762

Total costs 65090 164255 247585

Income ha−1 181260 529332 618800

Profit ha−1 116170 374581 371214

4 Results and Discussion

4.1 Agro ecological parameters in the different production sites

The Zapote Variety is only cultivated by the low technological level farmers. The Maradol

variety is the most predominant in the high and medium levels. These farmers buy the

plants in specialized nurseries. The harvest of Maradol starts at six months and the

Zapote variety seven months after transplanting. The productive period varies between

5 and 7 months with harvest cuts in an 8 day rhythm. The harvest must be realized

when the fruits present a maturation point of 25 to 35 % yellow to be sent to the

local market. For external market the fruit should show a trace of yellow color. Both

varieties present five productive months, considering that it shouldn’t be affected by

pests and diseases. In the medium and high level technologies farmers calculate 15 t

per cut and hectare, which fills a truck with 9000 fruits with an average weight of 1.7

kg approximately.

The evaluation of the agro ecological features in the six producing units presented a very

heterogeneous scenario among the producing units (Table 3). The cultivated density

according to the technology level varies between 1000 and 2140 plants ha−1.

6

Table 3: Agro ecological parameters in the different production sites.

Agro ecological parameters Cardenas Centro Huimanguillo Cunduacan Teapa Balancan

Level of technology low low medium medium medium high

Density (plants per hectare) 1800 1000 1400 2000 2140 2140

Sown surface area (ha) 2 1 3 3.5 to 5 6 20 to 40

Water quality low medium medium medium medium high

Cropping System temporary temporal temporary irrigation irrigation irrigation

Use of agrochemicals medium low medium high medium high

Water quality was analyzed in each site. Irrigation systems only exist in medium and

high production level units. The use of agrochemicals in reference to the interviews

done is according to the technology level.

The economical aspects (Table 4, Figure 1) vary in the production units shown mainly by

the technology level. The use of irrigation in the units of high and medium technology

has an influence in the yield of these units. The economic incomes are higher in the

high technology level. The production costs are significantly higher caused by machinery

and equipment investment such as tractors and modern systems of fertirrigation, which

allow a more precise application of fertilizers. The interviews showed average yields of

40 t ha−1 for the low technology level, 60 t ha−1 for the medium technology level and

80 t ha−1 for the high level. The production costs per hectare vary from $25,000 to

$40,000; $60,000 to $80,000 and $80,000 to $100,000 Mexican pesos, respectively.

Table 4: Economical parameters of papaya crops in different municipalities of Tabasco.

Economical parameters Cardenas Centro Huimanguillo Cunduacan Teapa Balancan

Type of Technology low low medium medium medium high

Cropping System temporary temporary temporary irrigation irrigation irrigation

Cultivated surfacewith papaya

10% 10% > 50% 30% > 50% > 50%

Post harvest manual manual manual manual manual manual

Yield (t* ha−1) 28 28 60 60 60 84

Production costs(Mex. pesos ha−1)

40,000 40,000 120,000 120,000 120,000 160,000

The low technology farmers represent 88% in Tabasco, according to the information

obtained from the surveys and it was also confirmed that the average plant density

that are sown in the low technology surfaces is of 1100 plants per hectare, 1600 in the

medium technology lands and 2200 in the high technology surfaces (Table 5). Height

of the plants, size of the stem and yield were strongly related to fertilization.

7

Table 5: Agro economical characteristics according to the applied technology.


Low Medium High

Plant density per hectare 1100 plants 1600 2200

Size of the plantation (ha) 1 to 5 5 to 10 10 or more

Type of cropping system Temporary Irrigation irrigation

Distance between plants (m) 3×3 3×2.5 2×2.5

Drainage Low Medium high

Height of the plants (m) 1.87 1.94 2.05

Stem diameter (cm) 30 44 46

Harvest calendar each 10 days each 8 days each 8 days

Harvest period 5 months 7 months 8 months or more

No. of harvest cuts/month 3 cuts 4 cuts 4 cuts

No. of harvest cuts/year 15 20 28

No. fruits/plant/cut 1 to 5 8 to 10 8 to 10

Average weight/fruit (kg) 2.5 2.00 to 3.00 2.00 to 3.00

Yield (t/ha) 28 60 84

4.2 Production costs

The concepts that build up the cost structure are variable and fix costs. The total cost is

the sum of the total variable cost (CVT) and the total fixed cost (CFT) (Baca Urbina,

2006) (Table 6).

Table 6: Comparative costs in the different technological levels (Mexican pesos per ha).


Low Medium High

Land preparation 3500 5000 5000

Tools and equipments 2260 44410 54490

Plants 1650 8000 11000

Sowing 2850 10500 13500

Irrigation 0 10000 20000

Fertilization 7325 7500 10220

Pests and disease control 24318 40863 44034

Weed control 0 3800 7200

Harvest 500 8925 9425

Total costs 42403 138998 174939

The finality of this feature is to determine the profitability for the producer comparing

the costs and benefits considering all the incomes and expenses, the money relative value

in time and interest rate. The differences among the levels of costs for the productive

8

cycle are influenced mainly by the acquisition of the plants (amount and variety) and the

agrochemical materials (fertilizers, fungicides and herbicides). The raw material costs in

the plantations with low technology level are 13193 pesos ha−1, following by the medium

level with 29101 and high level with 37369 pesos ha−1 (Table 7). It’s important to say

that the mentioned products are applied in a revolving way as preventions and in some

cases of more incidences. The prices for the agrochemicals are base to the brokers of

these products in March 2007.

Table 7: Raw material costs in the different technological levels (Mexican pesos perha).


Low Medium High

Plants 1650 10500 13600

Fertilizers 7325 7500 10620

Fungicides 3318 9051 11099

Herbicides 600 800 800

Paper for fruit packing 300 1250 1250

Total cost 13193 29101 37369

The variable costs are the only directly affecting production costs. In contrary, the total

fixed fabrication costs remain constant at any production volume. The total variable

costs increase in a direct proportion with the change that occurs in the production.

Table 8 presents the variable and fixed costs for the papaya production.

Table 8: Total costs in the different technological levels (Mexican pesos/ha).


Low Medium High

Variable costs 38133 59061 104829

Raw material 13193 29101 37369

Labor 24700 29600 63500

Water 240 360 360

Fuel 0 0 2400

Electricity 0 0 1200

Fix costs 18000 96000 78000

Rent 18000 18000 0

Administration 0 36000 36000

Sale costs (15 tons truck) $ 7000 x 6 months 0 42000 42000

Total costs 56133 155061 182829

9

The marginal contribution percentages characterizing the productivity level is 48% in the

lower level, 72% in the medium and 59% in the high. Each peso per sale is designated

to the fixed costs being of 52, 28 and 41% remaining, designated for the variable costs.

The security margin (SM) is the percentage in which the sales can be reduced before

possible loses.

SM (low technology) = (70000-37500)/70000 = 0.46 = 46%

SM (medium technology) = (210000-128000)/210000 = 0.39 = 39%

SM (high technology) = (294000-121875)/2940000 = 0.58 = 58%.

In the case of high technology, the security Margin of 58% indicates that the papaya

sales could be reduced to 58 % without financial loss. The neutral point of the enterprise

is 42% of the total sales volume. That is, if it is sold at a neutral point its security

margin is zero.

Table 9: Marginal contribution of the different technological levels (Mexican pesos/ha).


Low Medium High

Yield (t ha−1) 28 60 84

Price (Mexican pesos / kg) 2.50 3.50 3.50

Net sales 70000 210000 294000

Variable costs 38133 59061 104829

Marginal contributions 31867 150939 189171

Contribution percentage 48 72 59

Security margin (%) 46 39 58

4.3 Profitability of the different production levels

The initial investment varied from $44323.00 in low technology and $148670 in high

technology. The cash flows for five years ranged from $84481.00 in medium technology

to $406069.00 in high technology (Table 10).This was the case in the three levels that

presented values from $16,051 in the medium level to $117,494 Mexican pesos in the

high level (Table 10).

The relation profit/cost (BCR) ranged from 1.7 to 2.7 in the different technology is an

positive economic income, and so production is profitable (Table 10).

Our study shows that there’s a financial profitability in the three different production

levels. Most of low producers are located in Chontalpa and Centro sub regions mainly in

Cunduacan, Huimanguillo and Cardenas and represent 88.06% with 1-5 has cultivated.

This temporary system presents 6 months from sow time (1100 plants 3.00×3.00m

apart) to harvest and 5 or 6 of harvest as high average production. (1.85 per cut each

10 days are 3 cuts per month, total 15 cuts = 28 tons a year. Market price is 2.50

kg., and incomes per sales are $70,000.00, considering that disease and plague problems

have a 50% influence. It’s transplanted from June to August for the harvest between

10

Table 10: Investments effective flow and profitability indicators in the different techno-logical levels (10 Mexican pesos = 1 USD).


Low Medium High

Fixinvestment

2420 86630 103430

Deferredinvestment

1500 1500 1500

Labourcapital

36483 40476 43740

Totalinvestment

44323 1286806 148670

Effectiveflow

84481 219483 406069

V AN 23592 16051 117494

BCR 1.9 1.7 2.73

TIR 0.253773 0.200580 0.430864

Point ofEquilibrium

Sales should be 37,500Pesos to have no losses,therefore it must be solda minimum of 10,714 kgat $2.50/kg



February and June taking into account that in cold seasons the papaya consumption

lowers from December to January. The results give: V AN is 2359.20 USD, BCR is

1.9 and the equilibrium point is 3750.00 USD in order to avoid loses, it should be sold

at 10714 kg ant TIR is 0.253773 and this indicators show that the system is profitable.

Most of medium technology producers cultivated papaya in Cunduacan, Huimaguillo

and Teapa. This producers harvest each 8 days, 1 to 5 t ha−1 in an average of 3 t per

cut and 4 cuts per month with a yield of 60 t ha−1. In medium technology V AN is

1605.10 USD, BCR is 1.7, TIR 0.20 and the equilibrium point is 12800.60 USD and

36571 kg and indicators have shown that also this system is very profitable.

High technology producers grew their papaya in Balancan. These big producers sell

directly their products in a price of $3.50 per kg. The transplanting time in risk conditions

is March, April to harvest in September-February. It’s a cut each 8 days with an average

of 3t/ha during 7 months which is an average of 28 cuts per year with a yield of 84

t ha−1 (Table 10). In high technology level V AN is 11749.40 USD, BCR is 2.73,

TIR 0.430869 and the equilibrium point is 12187.50 USD with a minimum commerce

of 34821 kg. The indicators showed that all three levels are profitable and economically

viable.

4.4 Pro-form results

The aim of the analysis of the results or the loses or benefits is to calculate the real

net profit and net cash flow, which is the real benefit and it is obtained extracting

the incomes from all the cost that happen during the cropping season (Table 11). In

11

Mexico, it’s paid in 2007 (Based in IRS) the 28% of taxes. It’s called pro-farm because

this means projecting (normally 5 years) the economic results the producer will have.

We assume that the need of 5 year projection is necessary to have a good profit margin,

as well as crop rotation.

Table 11: Pro-form results in different technological levels.

YearVariables

1 2 3 4 5

Low level

Yield (t ha−1) 28 28 28 28 28

Income (Mex pesos ha−1) 70000 77000 84700 93170 102487

Production costs (Cv+Cf) 56133 61746 67920 74713 82184

Net cash flow 13867 15254 16780 18457 20303

Medium level

Yield (t ha−1) 60 60 60 60 60



Profit before taxes 54939 60433 66476 69824 76806

Taxes 28% 15383 16921 18613 19551 21506

Profit after taxes 39556 43512 47863 50273 55300

Services 26% 10285 11313 12444 13071 14378

INFINAVIT 5% IMSS 19.75+1.255 ceasing and retiring and salaries 2007

Profit after tax 29271 32199 35419 37202 40922

Profit after benefits 8894 8894 8894 8894 8894

Depreciation

Net cash flow 38165 41093 44313 46096 49816

High level

Yield (t ha−1) 84 84 84 84 84



Profit before taxes 111171 122289 134518 147970 162766

Taxes 28% 31128 34241 37665 41432 45574

Profit after taxes 80043 88048 96853 106538 117192

Services 26% 20811 22892 25182 27700 30470

INFINAVIT 5% IMSS 19.75+1.255 ceasing and retiring and salaries 2007

Profit after tax 59232 65156 71671 78838 86702

Profit after benefits 8894 8894 8894 8894 8894

Depreciation

Net cash flow 68126 74050 80565 87732 95596

12

Papaya production is profitable based on economic indicators considering pros and cons

of the troubles that the producers face in their crops. Therefore, it should be considered a

systematic planning of the investment program. From the small producers point of view,

from income and expenses control to training and technical assistance as well as having

a soil analysis before sowing, a good production process control, good farming practices

including a complete control of plagues and diseases so that the ecological equilibrium

of the environmental ecosystem can be kept. With few investments, profitability can

be achieved. If more productive and profitable systems are to be installed, it will be

necessary to have more investment.

5 Outlooks

In the last years papaya production was drastically reduced nation wide especially in

Tabasco. This is the result of the high level of disease and plagues indexes in the crops,

reducing the prices of the fruit, increasing the costs of materials and the low level of

technology that makes a low profit in the papaya production in Tabasco. The application

of low technology is profitable for the producers who crop 1-4 ha, even considering the

pest and diseases problems and dryness and water flooding. Their incomes can be raised

by adequate training and the use of good culture practices with an adapted technological

level which allows them to produce with higher yield and better quality more profit. It’s

possible to organize sustainable growing, harvest and commercializing structures based

in best culture practices, transparent fruit handling and high income for all papaya

producers in Tabasco.

References

Baca Urbina, G.; Evaluacion de proyectos; 40–65; McGraw-Hill/Interamericana de

Mexico; 2006.

Coss Bu, R.; Analisis y evaluacion de proyectos de inversion; Limusa S.A de C.V.

Grupo Noriega Editores; 2001.

Mendez Garrido, E. M.; Desarrollo rural integral de las zonas tropicales y subtrop-

icales de Mexico; Fundacion Produce Tabasco A.C. Mexico; 2005.

Mirafuentes Hernandez, F.; INIFAP; in: Memoria XIV Reunion Cientıfica-

Tecnologica, Forestal y Agropecuaria; INIFAP, Tabasco; 2001.

Plata, F. B.; La agricultura del nuevo milenio; Revista Agrotiempo; 8(82):6–7; 2000.

Pohlan, H. A. J., Gamboa Moya, W., Salazar Centeno, D., Mar-

roquın Agreda, F., Janssens, M. J. J., Leyva Galan, A., Guzman, E.,

Toledo Toledo, E. and Gomez Alvarez, R.; Organic horticulture in the trop-

ics: Situation and examples from Meso – America; Journal of Agriculture and Rural

Development in the Tropics and Subtropics; 108(2):125–150; 2007.

SAGARPA; Secretarıa de Agricultura, Ganaderıa, Desarrollo Rural, Pesca y Ali-

mentacion, Delegacion Estatal; 2001.

SAGARPA; Plan rector sistema nacional papaya. Diagnostico inicial base de referencia;

Estructura estrategica, SAGARPA - Secretarıa de Agricultura, Ganaderıa, Desarrollo

Rural, Pesca y Alimentacion, 1-37; 2005.

13

SAGARPA; Costos de produccion papaya Maradol- Roja; Ciclo: Perennes 2004-2005,

SAGARPA - Secretarıa de Agricultura, Ganaderıa, Desarollo Rural, Pesca y Ali-

mentacion; 2006.

Santesmases, M. M.; Diseno y analisis de encuestas en investigacion social y de

mercados. DYANE Version 2 ; 12–40; Ediciones piramide. Universidad de Alcala de

Henares; 2005.

Semillas del Caribe; Tecnologıa, Control de Plagas y Enfermedades; 2000; URL

http://www.semilladelcaribe.com.mx/paginas/5-5.htm.

Silva Torres, E.; Costos de produccion y comercializacion de papaya (Carica papaya

L.) cv. Maradol en San Pedro Balancan, Tabasco; Tesis, Universidad Autonoma de

Chapingo; 2002.

Wander, A. E., Didonet, A. D., Moreira, J. A. A., Moreira, F. A., Lanna,

A. C., Barrigossi, J. A. F., Quintela, E. D. and Ricardo, T. R.; Economic

viability of small scale organic production of rice, common bean and maize in Goias

State, Brazil; Journal of Agriculture and Rural Development in the Tropics and Sub-

tropics; 108(1):51–58; 2007.

14


Volume 109, No. 1, 2008, pages 15–50

Plant Genetic Resources: Selected Issues from Genetic Erosion to

Genetic Engineering

K. Hammer ∗1 and Y. Teklu 2

Abstract

Plant Genetic Resources (PGR) continue to play an important role in the development

of agriculture. The following aspects receive a special consideration:

1. Definition. The term was coined in 1970. The genepool concept served as an im-

portant tool in the further development. Different approaches are discussed.

2. Values of Genetic Resources. A short introduction is highlighting this problem and

stressing the economic usfulness of PGR.

3. Genetic Erosion. Already observed by E. Baur in 1914, this is now a key issue

within PGR. The case studies cited include Ethiopia, Italy, China, S Korea, Greece and

S. Africa. Modern approaches concentrate on allelic changes in varieties over time but

neglect the landraces. The causes and consequences of genetic erosion are discussed.

4. Genetic Resources Conservation. Because of genetic erosion there is a need for

conservation. PGR should be consigned to the appropriate method of conservation (ex

situ, in situ, on-farm) according to the scientific basis of biodiversity (genetic diversity,

species diversity, ecosystem diversity) and the evolutionary status of plants (cultivated

plants, weeds, related wild plants (crop wild relatives)).

5. GMO. The impact of genetically engineered plants on genetic diversity is discussed.

6. The Conclusions and Recommendations stress the importance of PGR. Their con-

servation and use are urgent necessities for the present development and future survival

of mankind.

Keywords: Plant Genetic Resources (PGR), crop plants, genetic erosion, genetic re-

sources conservation, GMO

1 Introduction

World population is expected to increase by 2.6 billion over the next 45 years, from 6.5

billion today to 9.1 billion in 2050. The world needs astonishing increase in food produc-

tion to feed this population. Plant genetic resources (PGR) constitute the foundation

upon which agriculture and world food securities are based and the genetic diversity in

∗ corresponding author1 Prof. Dr. Karl Hammer, Department of Agrobiodiversity, University of Kassel, Steinstrasse

19, 37213 Witzenhausen, Germany2 Dr. Yifru Teklu, Institute of Plant Genetics and Crop Plant Research, Gene and Genome

Mapping Unit, Corrensstr 3, 06466 Gatersleben, Germany

15

the germplasm collections is critical to the world’s fight against hunger. They are the

raw material for breeding new plant varieties and are a reservoir of genetic diversity.

Genetic adaptation and the rate of evolutionary response to selective forces depend on

inherent levels of genetic diversity present at the time a species experiences a threat to its

survival. Genetic diversity gives species the ability to adapt to changing environments,

including new pests and diseases and new climatic conditions.

Over the millennia, traditional farmers have given us an invaluable heritage of thousands

of locally adapted genotypes of major and minor crops that have evolved because of

natural and artificial selection forces (Myers, 1994). The genetic base of landraces, wild

and weedy relatives in which future breeding is based have been threatened by various

factors of genetic erosion. Erosion of these genetic resources along with accompanying

practices and knowledge that farmers use to develop, utilize and conserve crop genetic

resources could pose a severe threat to the world’s food security in the long term.

Loss of genetic variation may decrease the potential of species to persist in the face of

abiotic and biotic environmental change as well alter the ability of a population to cope

with short-term challenges such as pathogens and herbivores. Detecting and assessing

genetic erosion has been suggested as the first priority in any major effort to arrest loss

of genetic diversity. Generally, nevertheless, many national programs have not regarded

quantification of genetic erosion as a high priority, as apparent from the paucity of

information in the State of the World Report (FAO, 1996b).

With the further development of scientific and technical possibilities, the need for various

plant genetic resources will increase. Therefore, the results of unabated gene erosion

must by all means be reversed. Urgent action is needed to collect and preserve irreplace-

able genetic resources (Frankel, 1974). All effort should be made to cover this future

need by utilizing both in situ as well as ex situ maintenance. In situ means the setting

aside of natural reserves, where the species are allowed to remain in their ecosystems

within a natural or properly managed ecological continuum. This method of conserva-

tion is of significance to the wild relatives of crop plants and a number of other crops,

especially tree crops and forest species where there are limitations on the effectiveness

of ex situ methods of conservation. The ex situ form of conservation includes, in a

broad sense, the botanic gardens and storage of seed or vegetative material in gene

banks. Biotechnology has generated new opportunities for genetic resources conserva-

tion. Techniques like in vitro culture and cryopreservation have made it possible to

collect and conserve genetic resources, especially of species that are difficult to conserve

as seeds. DNA and pollen storage also contribute to ex situ conservation. No single

conservation technique can adequately conserve the full range of genetic diversity of a

target species or gene pool. Greater biodiversity security results from the application

of a range of ex situ and in situ techniques applied in a complementary manner, one

technique acting as a backup to the other techniques.

Advances in biotechnology have offered a new arsenal of methods to effectively utilize

genetic resources. Gene technology increased the possible use of distantly related trait

carriers as donors for the desired characteristics. However, the movement of genes across

species boundaries presents many opportunities for both expected and unexpected risks.

16

In addition to food safety, other concerns involve ecological risks, such as new or in-

creased resistance to insecticides and weed resistance to herbicides due to hybridization

or excessive selection pressure, changes in the ecological competitiveness of crops, and

the possible loss of genetic diversity in areas of crop origin (St Amand et al., 2000).

Transgenes conferring novel traits that enhance survival and reproduction may inadver-

tently disperse from cultivated plants to wild or weedy populations that lack these traits

and might generate similar but unwanted effects in their weedy relatives through gene

flow.

2 Plant Genetic Resources

2.1 Definition of Plant Genetic Resources

The term “genetic resources” was first used at a conference which took place under the

International Biological Program (Hawkes, 1997). The conference papers were pub-

lished in 1970 (Frankel and Bennett, 1970). Since then various attempts were made

to define plant genetic resources. According to the revised International Undertaking

1983 of the FAO, plant genetic resources were defined as the entire generative and veg-

etative reproductive material of species with economical and/or social value, especially

for the agriculture of the present and the future, with special emphasis on nutritional

plants. Brockhaus and Oetmann (1996) defined PGR as “plant material with a

current or potential value for food, agriculture and forestry”. A correlated definition

that appends a value of aggregation to PGR was given by FAO (1989). According to

this definition, plant genetic resources refer to the economic, scientific or societal value

of the heritable materials contained within and among species. They include materials

used in cytogenetic, evolutionary, physiological, biochemical, pathological or ecological

research on one hand, accessions evaluated for their agronomic or breeding propensities

on the other.

The work of Harlan and de Wet (1971) that starts with gene pools (Figure 1) has

formed a valid scientific basis for the definition of plant genetic resources. Plant breeders

recognized three major gene pools based on the degree of sexual compatibility (Harlan

and de Wet, 1971; Gepts, 2000). All crop species belong to a primary gene pool

together with such material with which they produce completely fertile crosses through

hybridisation. In contrast, all those plant groups that contain certain barriers against

crossing belong to the secondary gene pool. The tertiary gene pool includes groups

that can only be crossed with the help of radical new techniques. Plant breeders have

traditionally emphasized closely related, well-adapted domesticated materials within the

primary gene pool as sources of genetic diversity (Kelly et al., 1998). More recently,

however, plant transformation and genomics have led to a new quality which has been

defined by Hammer (1998) and Gepts and Papa (2003) as a fourth gene pool, whereas

Gladis and Hammer (2002) concluded that information and genes from other species

should be a special case for the third gene pool. The fourth gene pool should contain any

synthetic strain shown with nucleic acid frequencies, DNA and RNA, that do not occur

in nature (Figure 1). Transgenesis allows us to bypass sexual incompatibility barriers

altogether and introduce new genes into existing cultivars. It should be emphasized here

17

that the major function of transgenic technologies is not the creation of new cultivars

but the generation of new gene combinations that can be used in breeding programs

(Gepts, 2002).

Figure 1: The gene pool concept, established by Harlan and de Wet (1971) andan example of an organismoid or a hypothetically designed crop.

GP 4 GP 4

GP 4GP 4

Hybrids with GP-1Anoumalous, lethal or completely sterile

All species that can be crossed withGP-1 with at least some fertility

GP 1

Subspecies A:Cultivated races

Subspecies B:Spontaneous races

GP 1

Biological Species

Gene transfer possiblebut may be difficult

Gene transfer not possible orrequire radical techniques

GP 4 GP 3 GP2 GP 2 GP 3 GP 4

GP 1

b)a)

a) The gene pool concept, established by Harlan and de Wet (1971), modified.GP 1 The biological species, including wild, weedy and cultivated races. GP 2 Allspecies that can be crossed with GP 1, with some fertility in individuals of theF1 generation; gene transfer is possible but may be difficult. GP 3 Hybrids withGP 1 do not occur in nature; they are anomalous, lethal, or completely sterile;gene transfer is not possible without applying radical techniques. Informationfrom other genes refers to comparative genomic information on gene order andDNA sequence of homologous genes. GP 4 Any synthetic strains with nucleicacid frequencies (DNA or RNA) that do not occur in nature.

b) Example of an organismoid or a hypothetically designed crop with a genomecomposed of different gene pools and synthetic genes [for the explanation of thiscomplicated matter, see Gladis and Hammer (2002)].

2.2 Values of Genetic Resources

Human civilizations have benefited greatly from the domestication, conservation and

use of plants species used for agriculture and food production. For thousands of years,

farmers have used the genetic variation in wild and cultivated plants to develop their

crops. Genetic diversity is the basic factor of evolution in species. It is the foundation

of sustainability because it provides raw material for adaptation, evolution, and survival

of species and individuals, especially under changed environmental, disease and social

conditions (Hammer, 2004), and it will allow them to respond to the challenges of the

next century (Hammer et al., 1999). The future food supply of all societies depends

on the exploitation of genetic recombination and allelic diversity for crop improvement,

and many of the world’s farmers depend directly on the harvests of the genetic diversity

they sow for food and fodder as well as the next seasons seed (Smale et al., 2004).

18

The considerable genetic diversity of traditional varieties of crops is the most immediately

useful and economically valuable part of global biodiversity. Subsistence farmers use

landraces as a key component of their cropping systems. Such farmers account for

about 60% of agricultural land use and provide approximately 15-20% of the world’s

food (Francis, 1986). In addition, landraces are the basic raw materials used by plant

breeders for developing modern varieties.

Over the last few decades, awareness of the rich diversity of exotic or wild germplasm

has increased. This has lead to a more intensive use of this germplasm in breeding and

thereby yields of many crops increased dramatically. Domesticated tomato plants are

commonly bred with wild tomatoes of a different species to introduce improved resistance

to pathogens, nematodes and fungi. Resistance to at least 32 major tomato diseases

have been discovered in wild relatives of the cultivated tomato. Genes responsible for

promoting resistance to 16 of these have been bred into commercial cultivars, allowing

tomato production in areas where they could not otherwise have grown. Lodging was

one of the major constraints limiting further increases in yields in wheat production since

it prohibits the application of high amount of fertilizer. A search was therefore made

among wheat from different areas of the world to locate a suitable source of genetic

dwarfness to overcome this barrier. Norin 10, an extremely dwarf wheat landrace from

Korea found in Japan’s collections, proved to be a suitable source because of two genes,

Rht1 and Rht2, that caused dwarfing. Norman Borlaug speculated that by breeding

these genes into Mexican wheat lodging would be reduced and the plants would respond

to fertilizer application. As it turns out, these genes not only reduce lodging through

reduced height, they have direct effects on yield as a result of more efficient nutrient

uptake and enhanced tillering. Despite decades of active efforts by plant breeders to

control potato late blight, the disease continued to cause the loss of billions of dollars for

growers each year (Kamoun, 2001). The exploitation of genetic resistance remains the

most promising approach for the long-term control of late blight. The wild potato species

Solanum bulbocastanum is a source of genes for potent late blight resistance. Similarly,

the use of landraces and wild species in rice breeding has had an enormous impact on

rice productivity in many countries. For example, of the 6723 accessions of cultivated

rice and several wild species of Oryza screened for resistance, only one accession of wild

species O. nivara was found to be resistant and used to introduce resistance to grassy

stunt virus into cultivated rice (Ling et al., 1970). The use of Turkish wheat to develop

genetic resistance to diseases in western wheat crops is valued in 1995 at US $ 50 million

per year. Ethiopian barley has been used to protect Californian barley from dwarf yellow

virus, saving damage estimated at $160 million per year. Mexican beans have been used

to improve resistance to the Mexican bean weevil, which destroys as much as 25% of

stored beans in Africa and 15% in South America (Perrings, 1998). The diversity

of plants in different ecosystems brings a lot of pleasure and inspiration to people with

cultural and/or religious significance and the potential for income generation through

eco-tourism. Thus, it is important to appreciate the contribution to human welfare and

environmental sustainability made by all the three levels of biodiversity: (i) ecosystems,

(ii) species, and (iii) genetic diversity (IPGRI, 1993).

19

3 Genetic Erosion

From the beginning of agriculture, farmers have domesticated hundreds of plant species

and within them genetic variability has increased owing to migration, natural mutations

and crosses, and unconscious or conscious selection. This gradual and continuous expan-

sion of genetic diversity within crops went on for several millennia, until scientific princi-

ples and techniques influenced the development of agriculture (Scarascia-Mugnozza

and Perrino, 2002). The impact of humans upon biodiversity has gradually increased

with growing technology, population, production and consumption rates. The quest for

increasing food production and the ensuing success achieved in several crops has begun

to replace landraces by uniform, true-breeding cultivars. N.I. Vavilov and even Jack

Harlan are sometimes proposed as the first researchers that became aware of genetic

erosion in the 1920s and 1930s (Scarascia-Mugnozza and Perrino, 2002). In fact,

this phenomenon was postulated for the first time by Baur (1914, pp. 104-109), see

also Flittner (1995) and Hammer and Teklu (2006). So far, the American plant

breeders H. V. Harlan and M. L. Martini (Harlan and Martini, 1938) have been cred-

ited with first recognizing the problem of genetic erosion in crops (Brush, 1999). The

concept emerged forcefully between 1965 and 1970, in a period when crop improvement

had clearly demonstrated its power to transform local crop populations in industrialized

countries and in certain less developed regions (Brush, 1999) and the term gene erosion

was coined (Bennett, 1968). Brush (1999) defined genetic erosion in crops as the

loss of variability from crop populations. Variability refers to heterogeneity of alleles

and genotypes with their attendant morphotypes and phenotypes. Genetic erosion im-

plies that the normal addition and disappearance of genetic variability in a population

is altered so that the net change in diversity is negative.

3.1 Cases Studies

Several approaches have been employed to estimate the degree of genetic erosion that

a particular taxon faces in a certain region over a given time. Methods usually rely

on either the analysis of molecular data (Provan et al., 1999) and allozyme analysis

(Akimoto et al., 1999), or comparison between the number of species/cultivars still in

use by farmers at present time to those found in previous studies (Hammer et al., 1996)

or using the genetic assessment model presented by Guarino (1999) or using a checklist

of risk factors (de Oliveira and Martins, 2002). The most widely used figures in

estimating genetic erosion are indirect, i.e., the diffusion of modern crop varieties released

from crop breeding programs. The two case studies conducted by Hammer et al. (1996)

to estimate genetic erosion in landraces revealed that genetic erosion was found to be

72.4% in Albania and 72.8% in South Italy. Genetic erosion up to 100% was detected in

T. durum and T. dicoccon in some districts of Ethiopia (Teklu and Hammer, 2006).

Hammer and Laghetti (2005) used temporal comparison method to examine the loss

of genetic diversity in Italy. In the early years (from the 1920s to the 1950s), a relatively

high genetic erosion was observed (13.2% p.a.). From the 1950s until the 1980s erosion

rates between 0.48 and 4% p.a. were estimated. In the little island of Favignana there

was an erosion rate of 12.2% p.a. leading to the extinction of the last wheat landraces

20

of this island. The study of 220 land races with 147 forms in South Korea (Ahn et al.,

1996) showed a medium gene erosion of 74%. Akimoto et al. (1999) evaluated the

threat of genetic erosion faced by Asian wild rice in Thailand and reported that the

wild rice population was seriously destroyed and fragmented. Between 1949 and 1970,

the number of wheat varieties cultivated in China dropped from 10000 to only 1000

(Thrupp, 1998). The upland rice varieties in the Jinuo community of southern Yunnan

have been decreased from over 100 before 1980 to 65 in 1994. Recent statistics have

shown that variety numbers of crops in Swidden agro ecosystems in the community have

dropped since several improved varieties were introduced to the area within the past 10

years (Long et al., 1995). In India rice varieties have declined from an estimated

40,0000 before colonialism to 30,000 in the mid-19th century with several thousand

more lost after the green revolution in the 1960s. Also Greece is estimated to have lost

95% of its broad genetic stock of traditional wheat varieties after being encouraged to

replace local seeds with modern varieties developed by CIMMYT (Lopez, 1994). The

widespread adoption of high-yielding rice varieties has led to biological impoverty of

rice germplasm, as local rice varieties are abandoned for modern varieties (Gao, 2003).

IUCN has developed a system of categories of conservation status, the so-called IUCN

Red Data List Categories (IUCN, 1994). A review of the situation in southern Africa

using this system revealed that of the 23,000 species in the flora, 58 were extinct, 250

endangered, 423 vulnerable, and 1141 rare (Hilton Taylor, 1996). Hammer and

Khoshbakht (2005) have also used Mansfeld’s Encyclopedia (2001) and the IUCN

Red List of threatened plants (2001) to document the current genetic resources status

of agricultural and horticultural plants (excluding ornamentals) in Iran. About 200

threatened cultivated plants are considered and presented in the respective lists, among

them completely extinct crop plants such as Anacyclus officinarum and Bromus mango.

According to their report, there is even loss in crop plants on the species level.

In an attempt to determine the changes produced on genetic diversity as a result of

modern plant breeding, Khlestkina et al. (2004) compared the diversity of cultivated

wheat (Triticum aestivum) gene bank accessions collected up to 80 years ago in four

divergent geographical regions with materials that entered the gene bank about 50 years

later but originating from the same areas. They used a set of microsatellite markers and

reported a non-significant difference in both the total number of alleles per locus and

in the polymorphic information content when the material collected in the repeated

collection missions in all four regions were compared. They reported that an allele flow

took place during the adaptation of traditional agriculture to modern systems, whereas

the level of genetic diversity was not significantly influenced. Khlestkina et al. (2004)

only investigated the allelic changes occurred, over time, in the conserved materials.

Hence, their studies couldn’t fully address the actual genetic erosion occurred in the

field.

3.2 Major Causes of Genetic Erosion

The manifest cause of genetic erosion is the diffusion of modern varieties from crop

improvement programs (Brush, 1999). Much of the evidence for genetic erosion pre-

21

sented in the 1970/71 FAO survey (Frankel, 1973) is data on the diffusion of modern

cultivars (Kjellqvist, 1973). Landraces adapted to optimal local agronomic condi-

tions are probably the crop plant genetic resources that are most at risk of future loss

through habitat destruction or by replacement by introduced elite germplasm (Brush,

1995). With the development of scientific plant breeding, high-quality and homogenous

new varieties were quickly and widely distributed suppressing landraces. Yield (or yield

potential), which is the characteristics of most modern varieties, is the most important

criterion for the choice of a variety by a farmer (Heisey and Brennan, 1991). The

“Green Revolution” contributed and still undoubtedly contributes to the loss of genetic

diversity, even if the issue is not as cut and dried asWood and Lenne (1997) state it in

the equation “Green revolution = Loss of genetic diversity”. Population growth, urban-

ization, developmental pressures on the land resources, deforestation, changes in land use

patterns and natural disasters are contributing to abundant habitat fragmentation and

destruction of the crops and their wild relatives. The famine of the mid-1980s seriously

threatened Ethiopia’s biological resources (Worede and Mekbib, 1993). The study of

Stephen et al. (2002) showed a marked reduction in rice diversity in the northeastern

Philippines from 1996 to 1998 as a result of drought due to the El Nino phenomenon in

1997 and flooding due to two successive typhoons in 1998. According to Erskine and

Muehlbauer (1990), droughts of just a single season could result in people consuming

seed stocks, while successive years of drought can prompt changes in cropping patterns

and the geographic distribution of crops. Social disruptions or wars also pose a constant

threat of genetic wipeout of such promising diversity. Overexploitation and also the

introduction of invasive alien species are the other factors contributing to the loss of

genetic resources. More recently, global warming and a high degree of pollution have

also been recognized as further causes for the loss of biodiversity (Myers, 1994).

The modern world is placing a range of pressures on wild areas and on traditional agri-

cultural communities, and external interests (often dominated by economic or political

issues) strongly impinge (Tunstall et al., 2001). The major external forces advocate

the introduction of high-yield varieties, accompanied by mechanization and major chem-

ical inputs, as the means to increase total production and economic return. These forces

change the nature of the decision-making process dramatically; the farmer is encouraged

to grow high-yield varieties in monoculture using inputs of fertilizer and pesticides. In

many parts of the world, farmers were given several socio-economic incentives to replace

varieties that evolved within their agro-ecosystem with improved/introduced varieties

(Louette et al., 1997; Teklu and Hammer, 2006).

Often there are relationships of substitution between ecological functions of agrobiodi-

versity and external input (for example fertilizer or pesticides) (Hammer, 2004). That

means that external inputs can take over functions of agrobiodiversity and vice versa.

In homogenous, high-input agricultural systems, ecosystem functions that are missing

because of low agrobiodiversity are replaced with intensive management and external

inputs. Because of this, those components of agrobiodiversity whose functions can be

substituted at lower cost are particularly endangered. For example, in former years

many different fodder plants were grown in German fields (oats, barley, beans, clover,

22

Leucerne, fodder beets and potatoes). Now, corn is usually the only fodder plant, pos-

sibly supplemented by soybean meal as a protein component. Each of the species has

lost the race in its own fashion. Indigenous crops are adapted to the conditions of less

developed agriculture such as “crude land preparation and low soil fertility” (Harlan,

1975). As these conditions change with improved traction and fertilizer, the existing

adaptation of landraces turns from asset to liability. Tunstall et al. (2001) described

that landraces, which are grown because of their high resistance to pests during seed

storage, may become less important if improved storage systems are introduced.

Two types of genetic erosion can be distinguished in wild rice: the extinction of popu-

lations and the drastic change of genetic structure of populations (Gao et al., 2001).

The first type means the total loss of genetic resources, which results from complete

destruction of habitats, and all genotypes and/or alleles being lost, while the second

one originates from isolated local populations due to the deterioration of habitats. For

plants and some animals, area measurements of habitat patch sizes will provide a rea-

sonable basis to estimate population size (Brown et al., 1997), an important factor

determining survival of individuals. Hawkes (1983) reported that smaller area in tra-

ditional crops reduces diversity. The frequency distribution of the sizes of individual

populations is likely to reflect the way in which genetic variation is partitioned within

and among populations, with small populations being at increased risk of loss of alleles,

reduced heterozygosity, increased uniformity, enhanced inbreeding or possible extinction.

Brown et al. (1997) also indicated that the size and number of individual populations

are related to their ability to cope with both random (stochastic) fluctuations in the envi-

ronment and steady (systematic) long-term change. In some cases the loss of particular

crop varieties is not complete, but instead reduces surviving members of a landrace to

a few isolated populations (van Treuren et al., 1990). In such cases there is signifi-

cant risk of the ultimate loss of diversity, because smaller populations are vulnerable to

demographic and environmental stochasticity and the decline in fitness associated with

genetic drift and inbreeding (Frankel and Soule, 1981). Allozyme genetic diversity,

inversions and visible mutations all declined more rapidly in smaller than large popu-

lations (Montgomery et al., 2000). Two genetic consequences of small population

size are increased genetic drift and inbreeding. Genetic drift is the random change in

allele frequency that occurs because gametes transmitted from one generation to the

next carry only a sample of the alleles present in the parental generation. Genetic drift

changes the distribution of genetic variation in two ways: (i) the decrease of variation

within populations (loss of heterozygosity and eventual fixation of alleles), and (ii) the in-

crease of differentiation among populations. Every finite population experiences genetic

drift, but the effects become more pronounced as population size decreases (Falconer,

1989).

The problem of genetic erosion through inappropriate maintenance of ex situ collec-

tions is widely recognized. Genetic erosion can occur at many stages in the prepara-

tion, sub-sampling, exchange, storage and regeneration of seed (Sackville Hamilton

and Chorlton, 1997). They also highlighted loss of diversity through genetic shifts

and convergent selection during regeneration as a potentially severe and often under-

23

acknowledged problem. In the world collection, beyond the problem of duplication

among accessions, the security of ex situ conservation as a whole is endangered. About

half of all gene bank accessions urgently require rejuvenation, and in several countries

the percentage is even higher (Hammer, 2004). However, the different institutes are

suffering from financial problems, lack of staff and shortage of farms. The long-term

storage strongly reduces the metabolism and therefore highly limits viability and seed

vigor. According to Tsehaye (2002), durum wheat materials from the Ethiopian gene

bank have showed poor germination potential and vigor in the field, which is an indicator

of genetic erosion. Considerable evidence indicated that damage to chromosomes, some

of it resulting in heritable changes, takes place as seeds loose their viability. Studies in

barley and wheat showed that as storage age increases, chromosome aberrations (per

cell) increase (Gunthardt et al., 1953). Changes in the properties of DNA associated

with loss of viability in rye seeds, namely the loss of DNA-template activity (Holden

and Williams, 1984) and decreases in the molecular size of extractable DNA (Cheah

and Osborne, 1978), also have been observed.

Genetic erosion can also be caused by limited support for gene banks and in appropriate

focus or change in institutional policies. The work of gene banks in Eastern Europe to-

wards the end of the last century was reduced due to lack of money and employees. Only

international help was able to prevent catastrophic breakdowns (Frison and Hammer,

1992). New technological developments allow us to change agricultural products during

the processing phase so much that only a few basic raw materials are necessary. It is

possible, for example, with the aid of biotechnological methods to produce iso-glucose

from starch. In the USA, a large part of the present demand for sugar is met with iso-

glucose made from cornstarch. This has led to a strong decrease in the importance of

cane sugar (Knerr, 1991). Another approach attempts to supply widely differing qual-

ity products with a regionally well- adapted variety. For example, different oil qualities

are produced from canola (rapeseed, Brassica napus) in order to avoid importing oils or

growing other oil plants. Transgenic canola with high laurin acid oil content can be used

to substitute coconut or palm oil (Sovero, 1996), and reduce the demand for these oils

in the industrial countries. Buerkert et al. (2006) have reported genetic erosion in T.

turgidum L. and T. aestivum L. (including T. compactum Host) in Afghanistan because

of 23 years of war. They reached to this conclusion after they compared their survey

studies conducted in 2002 with the survey results of Vavilov (1997) and Vavilov

and Bukinich (1929). Other prominent causes of genetic erosion include the market

preferences of consumers for uniform grains, vegetables or foods (Myers, 1994), pest

and disease outbreaks, urbanization, population pressure, lack of recognition of current

or future value of genetic resources; poor monitoring and management, and lack of

sustainable breeding program.

3.3 Consequences of Genetic Erosion

Genetic uniformity leaves a species vulnerable to new environmental and biotic challenges

and causes heavy damage to the society. The Irish Potato famine was a dramatic

example of the dangers of genetic uniformity. The Irish population had reached about

24

8.5 million by 1845. Potatoes were the only significant source of food for about one

third of the Irish population. Farmers came to rely almost entirely on one very fertile

and productive variety known as ‘Aran Banner’. Unfortunately, this particular variety

was highly sensitive to the fungal disease late blight (Phytophthora infestans), which

had spread from North America to Europe. The blight destroyed the potato crop of

1845. Consequently, the Irish Famine of 1846-50 took as many as one million lives from

hunger and disease, and changed the social and cultural structure of Ireland in profound

ways. The famine also caused emigration of between 1.5 and 2.0 Million Irish.

By 1970 roughly three-quarters of the corn acreage in the US was planted in “Texas

T cytoplasm” corn. The Texas T cytoplasm results in individuals that are male-sterile.

This makes production of hybrid corn far less labor intensive, as there is no need of

detassleing. However, this maize is highly sensitive to host selective toxin (T toxin)

produced by race T of Cochliobolus heterostrophus, the casual organism of southern

corn leaf blight (Hooker et al., 1970). In 1970 this blight swept through fields of

“Texas T cytoplasm” corn and yield was reduced by approximately 710 billion bushels.

The cost to farmers was about $1 billion (Ullstrup, 1972). Browning (1988) argued

that the epidemic was “the greatest biomass loss of any biological catastrophe” and that

it was “a man-made epidemic caused by excessive homogeneity of the USA’s tremendous

maize hectarage.’ The loss of a significant fraction of the Asian rice crop to grassy stunt

virus also illustrates the same point. The catastrophic outbreak of coffee rust in 1970

caused great losses in Brazil with higher coffee world market prices as a consequence.

In 1916 a rust fungus destroyed about 3 million bushels of wheat in the United States,

roughly one-third of the crop. Other examples include the coffee rust epidemic in Ceylon

in the 1870s, the tropical maize rust epidemic in Africa in the 1950s and the blue mould

epidemic on tobacco in the USA and Europe in the 1960s (Marshall, 1977).

The loss of one species is estimated at being worth $203 million (Farnsworth and

Soejarto, 1985). These authors have calculated a total financial loss for the USA

through the loss of plant species at $3,248 billion dollars up to the year 2000. Presently,

33,730 plant species are characterized as being extinct or strongly endangered (Lucas

and Synge, 1996).

4 Genetic Resources Conservation

4.1 The Need for Conservation

Many species and varieties are becoming extinct and many others are threatened and

endangered. To reverse these unabated gene erosion, conservation of genetic diversity

is a fundamental concern in conservation and evolutionary biology, as genetic variation

is the raw material for evolutionary change within populations (Frankel and Soule,

1981). Conservation is the process that actively retains the diversity of the gene pool

with a view to actual or potential utilization Maxted et al. (2002). Utilization is

the human exploitation of that genetic diversity. The aim of conservation is to collect

and conserve adaptive gene complexes. Collection can be seen as a subject in its own

right and is not reviewed here – recently a first review appeared in this respect on

one of Vavilov’s gene centres (Vavilov, 1997) -– the Mediterranean (see Laghetti

25

and Hammer (2004). The raw materials of plant genetic resource conservation are

genes within gene pools, the total genetic diversity of the particular plant taxon being

conserved (Maxted et al., 2002). The product of gene pool conservation is utilised or

potentially utilisable genetic diversity.

The conservation of plant diversity is of critical importance because of the direct benefits

to humanity that can arise from its exploitation in improved agricultural and horticultural

crops, because of the potential for development of new medicinal and other products and

because of the pivotal role played by plants in the functioning of all natural ecosystems.

A great diversity of plants is indeed to keep the various natural ecosystems functioning

stably. No organism exists alone but all depend on a magnitude of interactions that

relate them together such as pollination and depend on a multitude of interactions that

relate them together (Prance, 1997). No doubt that primitive and wild gene pools

will continue to serve as important sources of genes for resistance to parasites or for

characteristics indicated by advances in science or technology or by changing demands

of the consumer. In the case of species, which are already used by human beings as

crops, it is very important to have a broad genetic base, to improve existing genotypes

when necessary.

4.2 A methodology for plant genetic resource conservation

Methods for germplasm conservation are determined by a number of factors. Maxted

et al. (1997a) proposed a model of plant genetic conservation, which summaries the

entire process of plant genetic conservation from selection of a target crop gene pool

through to its utilization (Figure 2). One of the first factors to be considered when

conserving botanical diversity is the efficient and effective selection of the target taxa.

The decision must have been taken that the target taxon is of sufficient importance to

warrant active conservation and that the gene pool is not currently adequately conserved

Maxted et al. (1997b). A practical approach to select target species could be the use

of the gene pool concept of Harlan and de Wet (1971). This concept is based on

the ease with which species hybridize with each other. The availability of information

on different gene pools enables the priority setting of target species to be incorporated

into the different conservation strategies. After selecting a taxa, a form of commission

in a form of formal statement containing the actual conservation activities including

the objectives of the conservation and justification for selection, how the material is to

be utilized, where the conserved material is to be safely duplicated, etc., and perhaps

indicating which conservation technique is to be employed should be formulated. A clear

and concise commission statement will help to focus subsequent conservation activities

Maxted et al. (1997a).

In formulating strategies for the conservation of any crop, it is essential to know its areas

of distribution, and identify regions where both collecting for conservation activities could

usefully be initiated. This will be due to a combination of high levels of genetic diversity

at the site(s), interest the user community in the specific genetic diversity found at or

believed to be found at the site, lack of previous conservation activities, and imminent

threat of genetic erosion (Maxted et al., 1997a). Hence, an ecogeographic survey

26

has to be undertaken to define the most appropriate conservation strategy (Maxted et

al., 1995), and specific conservation objectives should be formulated, involving both

ex situ and in situ components. The synthesis and analysis of ecogeographic data

enable conservationist to make vital decisions concerning, for example, which taxa to

be included in the target group, where to find these taxa, which combination of ex situ

and in situ conservation to use, what sampling strategy to adapt, and where to store

the germplasm or site the reserve (Maxted et al., 1995). Because the ecogeographic

data will rarely be sufficiently comprehensive to locate actual populations precisely; the

preparatory element of conservation activities should be followed by field exploration,

during which the actual populations are located (Maxted et al., 1997a). There are

two primary complementary conservation strategies, ex situ and in situ, each of which

includes a range of different techniques that can be implemented to achieve the aim of

the strategy. The products of conservation activities are primarily conserved germplasm,

live and dried plants, cultures, and conservation data. The conservation products are

either maintained in their original environment or deposited in a range of ex situ storage

facilities. To ensure safety, conservation products should be duplicated more than one

location.

4.2.1 Ex situ conservation

Ex-situ conservation is defined as the conservation of components of biological diversity

outside their natural habitat. In a broad sense, ex situ conservation of germplasm is a

practice that humans have used since the beginning of agriculture, to expand cultivation

and/or to colonize new lands and to ensure the spread of agriculture around the world

plants have traveled, during human migrations and along the ancient caravan routes,

from continent to continent. Moving from the Old to the New World and vice versa,

PGR have made many important contributions to agricultural production, diversification

and eating habits around the planet (FAO, 1959). Starting from the beginning of

agriculture, man has stored plants and seeds from one cycle of cultivation to the next

in different ways. Storage of germplasm also took place during migration.

The great genetic diversity to be found in the traditional stocks of peasant agriculture

in the centres of genetic diversity, where the wild or weedy relatives of crop species

can be found, were called gene centres or centres of diversity (Vavilov, 1926). Wild

and primary gene pools constitute the genetic resources available for the adaptation of

present-day cultivars, or for initiating new and potentially valuable pathways of crop

evolution (Frankel, 1974). As agriculture progressed with the beginning of scientific

plant breeding and human population increased, modern varieties were widely distributed

displacing landraces from cultivation. This increased the need to formally store plants

and seeds ex situ. Land races were then gathered together, which resulted in fairly

large collections, above all in the USA and in Russia (Plucknett et al., 1987). In

particular, the Russian scientist N. I. Vavilov amassed an unbelievable collection of

diversity in a Leningrad Institute (now St. Petersburg) by systematically collecting

material. With the rapid advancement of biotechnology in recent years, the ex-situ

conservation of living and genetic resources has increased in importance. At present,

over 6 million accessions are stored ex situ throughout the world (Plucknett et al.,

27

Figure 2: Proposed model of plant genetic resources conservation (taken fromMaxted et al. (1997a)

Selection of Target Taxa

Project Commission

Ecogeographic Survey/Preliminary Survey Mission

Conservation Objectives

Field Explorations

Conservation Strategies

Ex situ In situ(Sampling, transfer and storage) (Designation, management and monitoring)

SeedStorage

FieldGene bank

BotanicalGarden

In vitroStorage

PollenStorage

DNAStorage

GeneticReserve

On-farm

HomeGardens

Conservation ProductsSeeds, live and dried plants, in vitro ex plants, DNA, pollen, data

Conserved Products Deposition and Dissemination(Gene banks, reserves, botanical gardens, conservation laboratories, on farm systems)

Characterization/ Evaluation

Plant Genetic Resources Utilization(Breeding/ Biotechnology)

Utilization Products(new varieties, new crops, pharmaceutical uses, pure and applied research, on farm diversity, etc.)

28

1987). Of these, some 600,000 samples are maintained within the Consultative Group

on International Agricultural Research (CGIAR), the remaining 5.4 million accessions are

stored in national or regional gene banks (Table 1). Figure 3 shows the representation

of different crops in gene banks.

Table 1: Number of worldwide ex situ collections and their material (according to FAO(1996b))

Region Number of

gene

banks

% world Number of

accessions

% world

Africa 124 10 353,523 6

Asia 293 22 1,533,979 28

Europe 496 38 1,934,574 35

Near East 67 5 327,963 6

North America 101 8 762,061 14

Latin America and Caribbean 227 17 642,405 12

Sum 1,308 100 5,554,505 100

CGIAR system 593,191

Total sum 6,147,696

Figure 3: Major crop groups in ex situ gene banks (Source: Hammer (2004))

Only 30 crops make up the major part of the conserved plant material indicating that

most of the remaining 7,000 species of cultivated plants and many other valuable genetic

resources species have only been included on a limited scale in the gene bank collections

(Hammer, 2004)

4.2.1.1 Ex situ conservation techniques

29

Among the various ex situ conservation methods, seed storage is the most convenient

for long-term conservation of plant genetic resources. Traditionally, many crops are con-

served as seed in gene banks. This involves desiccation of seeds to low moisture contents

and storage at low temperatures (Kameswara Rao, 2004). However, there is a large

number of important tropical and sub-tropical tree species, which produce recalcitrant

seeds that quickly lose viability and do not survive desiccation, hence conventional seed

storage strategies are not possible (Roberts, 1973). For vegetatively propagated and

recalcitrant seed species, living plants can be stored in field gene banks and/or botanical

gardens. Major disadvantages of field gene banks, such as high maintenance costs, the

limited amount of genetic variation that can be stored and vulnerability to natural and

human disasters have led to efforts to develop in vitro conservation methods. In vitro

conservation is also used by botanical gardens for the reproduction of rare species. It

guarantees freedom from pest infestation and diseases. However, it is extremely labor

and cost intensive and can therefore only be used for special material as a long-term stor-

age possibility. The rapid developments in the field of biotechnology have opened up new

avenues for the conservation of germplasm in the form of tissue culture, cryopreserva-

tion, pollen storage and DNA banks (Callow et al., 1997). Cryo-conservation (storage

in extreme deep freeze situations) is accomplished with liquid nitrogen at -196 °Celsius

(Hammer and Hondelmann, 1997). It is also suitable for seeds and leads to a dra-

matic prolongation of germination rates. It allows for an extremely long storage of

many species. For in vitro maintenance cultures, it is the choice of preference because

somaclonal variation can be prevented. The problem with cryo-conservation is its high

cost, especially for technical equipment. A constant supply of liquid nitrogen also has to

be available at all times (Hammer, 2004). The methods of ex situ conservation have

been summarized in Table 2.

The ex situ conservation of large numbers of cultivated plants depends on the longevity

of the seeds. Most species belong to the orthodox seed type with a logarithmical

progression of shelf life as humidity and storage temperature are reduced (Hammer and

Hondelmann, 1997). The duration of seed viability can be estimated fairly precisely

by taking these aspects into account (Ellis and Roberts, 1980). The life expectancy

is determined through genotype. Care should be taken that viability not sink under 85%

(if the original rate is set at 100%), so that gene mutations will not occur in the seed

during storage.

4.2.2 In situ conservation

Storing genetic resources in collections as back-up seed stocks in ex situ collections does

not substitute for the evolution of crop plants in the fields of farmers. Plant populations

on farms have the capacity to support a greater number of rare alleles and different

genotypes than accessions in gene banks (Brown, 2000). As a result, in situ approach

was proposed in the early 1970’s for strictly agricultural purposes (Kuckuck, 1974),

but it has been scarcely utilized in the international crop germplasm system. In situ

conservation is defined as the conservation of ecosystems and natural habitats, and the

maintenance and recovery of viable populations of species in their natural surroundings

and, in the case of domesticated or cultivated species, in the surroundings where they

30

Table 2: Methods of ex situ conservation for various plant genetic resources (accordingto FAO (1996a))

Storage technology Storage material Function

Low temperature (-18°C),3-7% moisture content

Orthodox seeds Long-term storage (basiccollection), workingcollection

Dried seeds at cooltemperatures

Orthodox seeds Active and workingcollections, medium-termstorage

Ultra-dried seeds at roomtemperature

Orthodox seeds withlong-term viability

Medium to long-term storage(active and workingcollections)

Field gene banks Vegetatively-reproducedspecies, species withrecalcitrant seeds, specieswith long reproduction cyclesand minimal seed production

Short or medium-termstorage, active collections

In-vitro culture underslow-growth conditions

Vegetatively-reproducedspecies, some species withrecalcitrant seeds

Medium-term storage, activecollections

Cryo-conservation at -196°Cwith liquid nitrogen

Seeds, pollen, tissue orembryos that are suitable forin-vitro regeneration afterfreeze drying

Long-term storage

have developed their distinctive properties (UNEP, 1992). This definition encompasses

two distinct concepts (and techniques), which may be distinguished as “genetic reserve

conservation” and “on-farm conservation.” Both involve the maintenance of genetic di-

versity in the locations where it is encountered (i.e., in situ), but the former primarily

deal with wild species in natural habitats/ecosystems and the latter with domesticated

species in traditional farming systems. Maxted et al. (1997a) provide the following

working definitions for the two activities. Genetic reserve conservation is the location,

management and monitoring of genetic diversity in natural wild populations within de-

fined areas designated for active, long-term conservation. On-farm conservation is the

sustainable management of genetic diversity of locally developed crop varieties (land

races), with associated wild and weedy species or forms, by farmers within traditional

agricultural, horticultural or agricultural systems.

On-farm conservation is dynamic and is aimed at maintaining the evolutionary processes

that continue to shape genetic diversity. It is based on the recognition that farmers have

improved and grown genetic diversity and that this process still continues among many

farmers in spite of socio-economic and technical changes. Farmers play a big role through

their selection of plant material which influences the evolutionary process and through

their decisions to continue with a certain landrace or not (Bellon, 1996). Each sea-

31

son the farmers keep a proportion of harvested seed for resowing in the following year.

The farmer makes a conscious decision about which sample to retain for seed. For a

successful implementation of on-farm conservation, a fuller understanding of both crop

populations on the farming systems that produce them is needed to create active co-

operation between farmers and conservationists (Brush, 1995). On-farm conservation

assumes planned conservation in the framework of agricultural or garden production;

conservation must therefore take place during agricultural production. Modern vari-

eties, which often are more productive than the landraces, compete for this space with

landraces or wild plants. Therefore, financial or other incentives have to be built into

the system to safeguard future conservation. These requirements can be more easily

attained in developing countries. Subsistence farming tolerates a multitude of cultivated

plant species and forms in mixed culture and should be considered a living conservation

reservoir (Esquivel and Hammer, 1988).

Table 3: Number of species of wild plants, plant genetic resources (PGR) and cultivatedplants in the world (after Hammer (2004))

Higher plants PGR amonghigher plants

Cultivated plantsamong higher plants

Number 250,000 115,000 7,000

Wild plant material is usually conserved in its natural habitat. Compared with the rela-

tively small number of cultivated plant species, the plant genetic resources of wild plants

are quite numerous (Hammer, 2004, see Table 3). General protective measures can

therefore be of great importance to a large number of plant genetic resources. Protected

areas include national parks, biosphere reserves and Nature parks, which can be divided

into areas of varying protection, as well as riparian or wetland areas (Schlosser et al.,

1991). Policy strengthening, establishment of nature reserves and protected areas with

rich wild populations, management promotion, environmental education and training

(especially in local communities), adoption of indigenous knowledge, and local peoples’

participation can strongly support in situ conservation of agro-biodiversity (Long et al.,

2003).

4.3 Comparison of the different conservation measures

Conservation measures have often been critically evaluated. Many supporters of the

in situ strategy consider ex situ methods to be at best a transitional method leading

to further in situ maintenance (Lande, 1988). The differing standpoints have been

formulated in various international documents and treaties.

It is important that criticism of ex situ maintenance includes the limited possibilities

of evolution available with this method. In gene banks, conservation of the material is

handled in such a manner as to exclude natural evolution. This has to do with long-

term seed storage on the one hand, which strongly reduces the metabolism and therefore

strongly limits evolution. On the other hand, gene banks often have to grow the plant

32

material in areas that are far away from its place of origin, and this can easily result in

changes in population composition. Additional points of criticism are that insufficient

equipment and facilities are available to gene banks, that long-term storage is overrated,

and that the necessity of reproduction is underrated. Ex situ collections are not going

to be the universal means of preventing the results of gene erosion. The collections will

always be limited and gene banks will only be able to include a portion of all genetic

resources (Hammer, 2004).

The advantages of in situ conservation are undisputed in order to maintain a large

wealth of species, at the same time guaranteeing further evolutionary adaptation. The

possibilities of easily gaining access to the material are positive aspects of ex situ main-

tenance. Also, a vast amount of material of the most important plant groups, mostly

in the infraspecific area, can be safely conserved. Above and beyond this, systematic

documentation and characterization can be carried out more easily. From the side of

the user, the major criticism of in situ conservation lies in the difficulty of obtaining

access to the material for basic and breeding research. Furthermore, in many cases, it

is easier to conserve a viable population in situ than ex situ. This is certainly true of

tree species. Further comparison of the advantages and disadvantages of the different

conservation methods is presented in Table 4.

Table 4: Advantages and disadvantages of the different conservation methods (Kjaeret al., 2001).

Maintenancemethod

Advantages Disadvantages

In situ • Interactions with other species andorganisms are possible

• Interspecific and infraspecificvariations can be combined

• Can also be used for vegetativelyreproducible species or those withrecalcitrant seeds

• Requires large area for maintenance

• Only a small number of genotypescan be managed this way. Does notprotect against epidemics, diseases,etc., possible losses

• Access to the material is difficult

In situ orOn-farm

• Further evolution through naturalevolution and choice of varieties ispossible

• No conservation of the status quo,selection

• Gene erosion is possible

33

(Table 4 continuation)

Maintenancemethod


Ex situ Seedbanks

• Genetic status quo of the storedseeds can be maintained withappropriate reproduction strategy

• Propagules ready for use (althoughthe amount of seed typically is toolimited to serve as input tocommercial use)

• Little space required (at least forspecies with small seeds)

• Intra- and inter-population can beeasily conserved provided speciesrange adequately sampled

• Seed can be conserved far away fromthe in situ environment if requested

• No further evolutionary developmentdependent on the surroundingenvironment

• Problems with the maintenance ofrecalcitrant and vegetativelyreproducible species

• Facilities and large amount of spacenecessary for storage (large seeds)

• The original surrounding flora is notconserved as well

• Regeneration needs space and ismoney and labor intensive

• Only a limited portion of thevariability is collected and maintained

• Change of population structurethrough reproduction of populationsthat are too small

• ‘Short term storage rather thanconservation’ for the majority ofspecies

Field Genebanks

• Can conserve genetic resources in thehabitats of expected use

• Can develop into multiple populationconservation programmes where newintrapopulation variation is developedas response to different conditions ofgrowth or selection criteria

• Can be combined with utilization

• Can function as seed sources allowingrapid procurement of seed incommercial scale in earlydomestication

• Many areas required

• Spatial isolation to conservepopulation identity required

• Lack of pollinators may causeproblems

• Relatively expensive if not combinedwith utilization

Botanicalgardens andarboreta

• Botanical gardens are often part ofvery stable institutions and likely tobe continuously maintained bytrained staff

• Can be combined with demonstrationand education.

• Suitable site(s) required

• Difficult to collect seed due tohybridization

• In general not apt for conservation ofinter and intra- population variation(requires a larger number ofindividuals than usually planted inbotanical gardens/arboreta).

Tissueculture

• Little space needed

• Good for vegetative material andrecalcitrant species

• Aseptic conservation (minimizesdisease risk)

• Short time required to producepropagules for use

• High technical outlay

• Expensive facilities required

• Sampling problems (representativeindividuals and within individual)

• Difficult to conserve adequatenumber of genotypes

• Protocols are specific for species andoften even for genotypes

• Problems of soma-clonal variationand early maturation

34

(Table 4 continuation)

Maintenancemethod


DNA • Little space needed

• Can be used anywhere

• Future method of last resort inisolated cases

• Is not a germplasm conservationmethod per se

From the viewpoint of plant genetic diversity for food and agriculture, the diversity of

(1) cultivated plants, (2) wild relatives of cultivated plants, (3) introgressions between

cultivated plants and their relatives, and (4) weeds should be differentiated. Although

a different conservation strategy may be the most appropriate modus operandi for each

of these categories and for each specific group within these categories, the integrated

use of the different methods for conservation is necessary depending on the categories

of diversity and diversity groups. It is also necessary to consider different economics of

the countries. The argumentation scheme, which was based on is based on the methods

of conservation (ex situ, on-farm, in situ) as well as on the type of diversity, species

diversity and diversity of the ecosystem, has been proposed by Hammer et al. (2003)

(Table 5).

Table 5: Conservation methods for different categories of diversity rated by their im-portance for specific groups of diversity (Hammer et al., 2003).

Method of conservation

on-farm (agro-ecosystems)Category of diversity ex situ

(genebanks) Developingcountries

Developedcountries

in situ(other ecosystems)

Infraspecific diversity C** C*** C** C◦

R* R*** R* R***

W** W*** W* W*

Diversity of species C* C*** C** C◦

R* R*** R* R**

W** W*** W** W*

Diversity of ecosystems C◦ C*** C* C◦

R◦ R*** R** R**

W◦ W*** W*** W*

The number of stars indicates the relative importance of the methods for the various diversitygroups. C= Crop species, R = Wild Relatives of Crop Species, W = Weeds◦ = no importance, * = low importance, ** = important, *** = very important

35

4.4 The economics of plant genetic resources conservation

It looks much different when we talk about costs. The high costs for ex situ maintenance

are visible, and it is possible to obtain an overall picture from the concrete figures for

material and equipment listed in the global report. According to Plan et al. (1994),

the conservation of one seed sample costs approximately 0.50 German marks a year

(calculated according to Smith (1984) and Parez (1984). The entire volume of finances

for the gene bank Gatersleben in the year 1992 (payroll, investment costs, overhead)

came to 4,790,800 German marks (Thoroe and Henrichsmeyer, 1994). Taking

100,000 samples into account, the costs for the maintenance of one sample comes to

approximately 50 German marks. Included in this estimation are not only the costs for

the maintenance of the material, but also research, without which the collection cannot

be vitally maintained over a longer period. The case studies made to estimate annual

cost of maintaining different crops is given in Table 6.

The economics of plant genetic resources, with relation to gene banks, is going to estab-

lish itself as new research area (Virchow, 1999). The basis for these considerations is

usually the search for larger budget-cutting possibilities. But since gene banks have of-

ten already been degraded to the role of harvest silos, such examples are highly unsuited

for a general estimate of costs. The economic conclusions reached by such studies could

further burden the already unstable situation of global ex situ conservation.

Table 6: Annual costs of maintaining cassava, wheat and maize germplasm in field genebank, in vitro and seed conservation.

Conservation Technique Crop CG Centre Total cost/accession (US $)

Field Cassava CIAT 17.09

In vitro Cassava CIAT 26.22

Seed Wheat CIMMYT 0.05

Seed Maize CIMMYT 0.33

Source: Epperson et al. (1997).

5 The Impact of Genetically Engineered Plants on Genetic Diversity

Genetic engineering has potential to solve problems that have proved intractable us-

ing conventional breeding approaches, such as developing crop varieties with in-built

resistance to key pests and diseases and tolerance to stresses such as drought. Genet-

ically modified (GM), or transgenic, organisms are created through genetic engineering

techniques that allow genetic material to be moved between similar or vastly different

organisms with the aim of changing their characteristics for a purpose. In developing

an engineered plants, genes are introduced into a genome using Agrobacterium tumefa-

ciens, a pathogenic bacterium that naturally transfers DNA to plants during the disease

process (Gelvin, 2000) and using biolistics or a variant, particle discharge (Birch,

1997). Another method associated with transgenic technology is the process of nuclear

36

transfer, which is a cloning technique. Since the birth of the first successful transgenic

plant in the beginning of 1980’s, tremendous accomplishments associated with trans-

genic biotechnology have been achieved and rapid application of the biotechnology in

agriculture has substantially benefited crop genetic improvements. As a consequence,

a great number of genetically modified crops (GMC) have been released and commer-

cialised (e.g. Huang et al. (2002). New cultivars of maize (Zea mays L.), soybean

(Glycine max), cotton (Gossypium spp.), papaya (Carica papaya), tomatoes (Lycoper-

sicon esculentum), canola (Brassica napus), and others have been developed that carry

additional genes conditioning traits as herbicide tolerance, insect resistance, or virus

tolerance. From 1996 to 2004, the global area of biotech crops increased more than

47 fold, from 1.7 million hectares in 1996 to 81.0 million hectares in 2004, with an

increasing proportion grown by developing countries. More than one-third (34%) of

the global biotech crop area of 81 million hectares in 2004, equivalent to 27.6 million

hectares, was grown in developing countries where growth continued to be strong. The

estimated global area of approved biotech crops for 2004 was 81.0 million hectares up

from 67.7 million hectares in 2003. Approximately 8.25 million farmers in 17 countries

grew biotech crops in 2004 (James, 2005).

Domesticated plants and their wild relatives usually belong to the same biological species

and they often hybridize and give rise to viable and fertile progenies (Harlan and

de Wet, 1971; Ellstrand et al., 1999), if wild and domesticated forms are sexu-

ally compatible, grow within pollinator flight distance (in the case of insect-pollinated

species), and their flowering times overlap at least partially. Such hybridization may

lead to gene flow: ‘the incorporation of genes into the gene pool of one population from

one or more populations’ (Futuyma, 1998). Many cultivated plants hybridize spon-

taneously with wild or weedy relatives (Small, 1984; Ellstrand et al., 1999). For

example, cultivated rice and its wild relatives O. rufipogon have sympatric distribution

and overlapping flowering times, which meets the spatial and temporal conditions for

transgene escape from cultivated rice to its wild relatives (Lu et al., 2003). Though cul-

tivated sorghum is largely self-pollinated with outcrossing rate of 2-30% (Schmidt and

Bothma, 2006), analyses of progeny segregation, allozymes, and RFLPs reveal crop-

specific alleles in wild S. bicolor when it co-occurs with the crop in Africa, suggesting

that intraspecific hybridization and introgression are common (Aldrich and Doebley,

1992). Studies carried out to measure spontaneous hybridisation between wild radish

(Raphanus sativus) and cultivated one (Klinger et al., 1991) and with Sorghum bi-

color and Sorghum halepense (a widespread weed) (Arriola and Ellstrand, 1996)

demonstrated that spontaneous hybridisation does take place (for a recent review see

Ellstrand (2003). With transgenic plants, the problem of gene flow, which may

ultimately cause possible ecological risks, has acquired special significance.

5.1 Consequences of gene flow

Transgenes coding for novel traits such as resistance to biotic and abiotic stresses

could have the potential to enhance ecological fitness of wild and weedy genotypes

(Ellstrand and Elam, 1993; Snow, 2003) and thus cause ecological problems. For

37

example, wild sunflower populations host many of the same herbivores and diseases as

cultivated ones (Seiler, 1992) and crop genes can easily backcross into wild sunflower

populations (Whitton et al., 1997). Snow (2003) studied a crop-developed Bacil-

lus thuringiensis (Bt) transgene, cry1Ac, in backcrossed wild sunflower populations and

found that a transgene derived from a crop has the potential to increase the fitness

of wild plants, and an increase in frequency in wild populations. The spread of trans-

genic herbicide resistance is likely to pose challenges for controlling weeds and unwanted

“volunteer” crop plants (Snow et al., 1999). Other possible risks are that transgenic

phenotypes with altered fitness could change in abundance in the ecosystem, with un-

wanted effects on other species and on ecosystem integrity, or that the ecosystems are

affected indirectly by the transgenic plants (Jorgensen et al., 1999).

Both genetic and geographic barriers to gene flow from crop to wild sunflower are mini-

mal (Snow et al., 2002). Hence, simple co-existence of GE and non-GE crops might be

impossible. For instance, there are now scientific evidences for cultivated rice outcross-

ing to non-GE rice (Lu et al., 2003; Gealy et al., 2003; Chen et al., 2004). Cultivation

of GE rice will therefore cause weedy strains of O. sativa such as “red rice” and the

wild relative, O. rufipogon to become contaminated with the GE transgenes (the GE

DNA insert). There are concerns that if red rice becomes tolerant to the herbicide

used in conjunction with a GE herbicide-tolerant rice, it will become more difficult to

control (Gealy et al., 2003; Chen et al., 2004). The GE contaminated populations

of wild and weedy species of rice are likely to be persistent, becoming reservoirs of GE

transgenes for further contamination. A loss of genetic diversity of domesticated and

wild relatives is cited among the potential drawbacks of the introduction of transgenic

crops (Berthaud and Gepts, 2004). When alien transgenes escape to and express

normally in wild relatives and weedy species, the transgenes will persist and disseminate

within the wild or weedy populations. This will lead to contamination of the original

populations of the wild relatives, and even to the extinction of endangered populations of

the wild relatives in local ecosystems (Ellstrand and Elam, 1993). Examples of ge-

netic assimilation or extinction by displacement of native allelic diversity are provided in

date palm (Phoenix dactylifera), olive (Olea europaea), and coconut (Cocos nucifera)

(Bronzini et al., 2002). Furthermore, natural hybridisation with cultivated rice has

been implicated in the near extinction of the endemic Taiwanese taxon, O. rufipogon

ssp. formosana (Small, 1984). Small-scale farmers generally maintain a range of ge-

netic diversity on their farm to meet their various needs and to be self-reliant. Genetic

assimilation and displacement of genetic diversity may constrain the livelihood of subsis-

tence farmers. The presence of transgenic volunteers in crop fields would contaminate

harvest with transgenic seeds and prevent the farmer from obtaining a ‘non-genetically

modified crop’ label for this product. Transgene contamination has been found in local

traditional varieties of maize in Mexico (Quist and Chapela, 2001). The escape and

persistence of transgenes in environment will also make effective in situ conservation

of wild genetic resources more difficult. Genetically modified crops cause much trouble

particularly in centres of diversity where crops are grown along with their wild relatives.

38

Most alien genes carried by genetically modified agricultural products are not from crops,

instead, they are from other organisms or microorganisms, even from an artificially syn-

thesized origin. These genes may completely alter the natural habit of crop species and

significantly change wild relatives of the crop species when transgene escape happens.

As a consequence, the environmental safety, particularly the agricultural ecosystems

might be under their negative influence (Ellstrand et al., 1999). The insertion of

transgenic DNA may bring about small-scale rearrangements of the transgene and na-

tive DNA sequences at the insertion site (Windels et al., 2001). The interactions of

transgene with other genes in the genome (“background effect”) may affect the overall

level of expression of the trait. Through recombination, genes belonging to a specific

variety can migrate into new genetic backgrounds where new linkages and gene interac-

tions may modify the expression of transgenes in an unpredictable fashion (Berthaud

and Gepts, 2004). When more than one sequence is introduced or if a transgene is

similar to a native sequence in the genome, then gene silencing can take place (Comai,

2000).

Some crop plants have been genetically engineered to produce pharmaceuticals and in-

dustrial chemicals (GE “pharm” crops). These pharm crops are not intended to be eaten

by humans and animals, but to be used by drug companies or in industrial processes.

The compounds produced by these plants are often biologically active chemicals and all

are potentially toxic to animals and humans.

Apart from the specific problems with GMOs, there is a more general effect. The use of

GMOs speeds up the breeding process and consequently leads to high in the agricultural

production, which results in a high genetic erosion. But this is the consequence of all

modern technology.

6 Conclusions and Recommendations

Thousands of genetically distinct varieties of our major food crops owe their existence

to years of evolution and to careful selection and improvement by our farmer ancestors.

Nevertheless, processes that once took hundreds or thousands of years to develop could

then be carried out within decades or even years under human influence (Hammer,

2004). There has been a significant loss of genetic diversity during the last l00 years

and the process of gene-erosion continues (Hammer et al., 2003). With genetic ero-

sion it is not only genetic resources that are under threat of disappearance but also

the indigenous knowledge of selecting, utilizing, and conserving these materials that

has been accumulated for thousands of years. Erosion of crop genetic resources could

pose a severe threat to the world’s food security in the long term since loss of genetic

variation may decrease the potential for a species to persist in the face of abiotic and

biotic environmental change as well alter the ability of a population to cope with short-

term challenges such as pathogens and herbivores. It is also threatening the genetic

base of many important crops in which future breeding is based. As a result, the loss

of biodiversity belongs to one of the central problems of mankind, next to other im-

portant matters such as climate change and securing an adequate supply of drinking

water. Paradoxically, in many parts of the world, although it is generally accepted that

39

significant amount of genetic erosion has occurred and is still occurring, there is little

data on its amount and extent. Without remedial action, genetic erosion will inevitably

increase, and the costs of replacement of diversity needed in the future by the com-

munity will be much greater (Hammer, 2004). Future progress in the improvement of

crops largely depends on immediate conservation of genetic resources for their effective

and sustainable utilization. It is widely agreed that the primary solution to the genetic

impoverishment of crop germplasm is genetic conservation and utilization in breeding of

the vast genetic variation found in populations of the wild progenitors and landraces of

cultivated plants (Frankel and Bennett, 1970; Tanksley and McCouch, 1997).

The discovery, collection, and conservation of potentially valuable but endangered plant

genetic resources is a primary obligation of all countries and institutions adhering to

the FAO international undertaking on plant genetic resources (Hammer et al., 2003).

A better characterization and understanding of genetic diversity and its distribution is

essential to efficiently exploit the available resources in more valuable ways. It is crucial

to efficiently design collecting trips and conservation projects (Teklu and Hammer,

2006). The value of diversity is in its use (Gao, 2003).

Since the beginning of the 70s of the last century an effective program has been devel-

oped for collecting, conserving and using of plant genetic resources, which was called

“plant genetic resources movement” (Pistorius, 1997). But step by step parts of this

program have become outdated. Recently, a paradigm shift in the discipline of plant

genetic resources has been observed (Hammer, 2003) which includes 1) the mainte-

nance of material (in situ instead of ex situ), 2) the enforced inclusion of neglected and

underutilized cultivated plants, 3) the methods of quantifying genetic diversity between

different cultivated plant taxa, 4) the methods of analyzing genetic diversity among the

different cultivated plant taxa, 5) their evaluation and 6) their reproduction.

The best method of conservation is the use of complementary approach of the different ex

situ and in situ conservation techniques. Since part of the worldwide ex situ collections

is endangered, priority should be placed on securing and providing financial support

for existing collections. The regular regeneration of material is essential and must be

made possible (Hammer, 2004). The expansion of strong national programs should be

supported as an important basis for a functional global plan. Support for networks of

cooperation in the area of plant genetic resources must also be improved. It is always

necessary to conserve a large number of collections of a particular taxon. The classic

example of this was the screening for resistance against the grassy stunt virus of rice at

the International Rice Research Institute in the Philippines. Under the 6723 accessions

of cultivated rice and several wild species of Oryza screened for resistance, only one

accession of wild species O. nivara was found to be resistant and used to introduce

resistance to grassy stunt virus into cultivated rice (Ling et al., 1970). The principle

of prevention (Noah’s Ark principle) tells us to maintain as much material as possible.

There is presently no scientific method, except the identification of duplicates, which

can give us a secure assessment as to which parts of the collections are expendable.

Apart from conservation, creation of sustainable agricultural systems that actively use

as much biodiversity as possible must remain the major goal. Only in use can diversity

40

be appreciated enough to be saved, only in use it can continue to evolve, and thus

retain its value (Partap, 1996). Hence, there should be an ultimate linkage between

conservation and utilization.

Biotechnology offers us a new arsenal of methods for the study of genetic resources,

but also for certain conservation techniques. Gene technology increases the possible use

of distantly related trait carriers as donors for the desired characteristics. Most of the

crop cultivars that are developed are compatible inter se but they are also compatible

with related wild or weedy relatives, suggesting that gene flow has always taken place.

The possibility of transgene flow from engineered crops to other varieties, to their wild

relatives or to associated weeds is one of the major concerns in relation to the ecological

risks of the commercial release of transgenic plants (Messeguer, 2003). It is currently

impossible to prevent gene flow between sexually compatible species in the same area.

Pollen and seeds disperse too easily and too far to make containment practical (Snow,

2002). It is therefore necessary to understand genetic relationships and actual gene flow

frequencies between the transegenic crop and wild/weedy relatives or landraces, to know

geographic distribution patterns and flowering habits of cultivated and wild crop species,

and to understand other factors influencing the gene flow. This will facilitate the effective

prediction of transgene escape and its potential ecological risks, and the development of

strategies to minimize the escape of alien transgenes. Empirical research is also needed

to evaluate the persistence of transgenes in the recipient populations and its effect on

fitness should be measured to fully assess the impact of gene flow of transgenes.

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Volume 109, No. 1, 2009, pages 51–63

Factors Influencing Irrigation Technology Adoption and its Impact

on Household Poverty in Ghana

Adetola I. Adeoti 1

Abstract

The treadle pump technology was promoted and disseminated as an alternative to tra-

ditional rope and bucket for irrigation in Ghana by the International Non-Governmental

Organization, Enterprise Works. The aim is to improve output, increase incomes and

consequently reduce poverty among farm households. The paper employed the Heck-

man two-stage and the Ordinary Least Square procedures to identify the factors that

influence adoption of the technology and the impact of adoption on the poverty status

of farm households. Farm and household level data were obtained from 108 farmers

consisting of 52 adopters and 58 non-adopters. The results demonstrated that availabil-

ity of labor and increases in number of extension visits per year are factors that increase

the probability of adoption. The results also showed that increase in irrigated area has

the highest impact on poverty followed by adoption of treadle pump and literacy level

of farmers.

Keywords: Irrigation technology, treadle pump adoption, poverty, Ghana

1 Introduction

The occurrence of erratic rainfall have created uncertainty for agricultural production

and emphasized the need for irrigation in Africa. The traditional system of irrigation

comprises of the use of either rope and buckets to lift and distribute water from shal-

low open wells or watering cans to lift water from streams. Although the low capital

requirement of these traditional technologies makes them advantageous and affordable,

their low delivery capacity and labor intensive nature make them highly unfavorable to

African production conditions (Kamara et al., 2004). Improved water lifting technolo-

gies, with relatively high efficiencies such as motorized pumps, have been tried but have

been found to be favorable mostly to large-scale farmers. For small-scale farmers, who

usually irrigate relatively small plots of land and operate relatively small capital, such

technologies are unaffordable. This lack of simple, affordable and well adapted water de-

velopment technologies, suitable to the production conditions and needs of smallholder

farmers in sub-Sahara Africa, among others, is a serious handicap to efforts for achieving

food security in the continent (Hyman et al., 1995; Brabben and Kay, 2000).Today

a substantial variety of low-cost, affordable water development options exist, including

1 Adetola I. Adeoti, Dept. of Agricultural Economics, University of Ibadan. Ibadan. E-mail:[email protected]

51

treadle pumps (TP 1). The TP is a low-lift, high capacity, human powered water lifting

pump. It is suitable for irrigating agricultural land of less than one hectare and are

considerably less expensive than motorized pumps. Also, it cost much less to operate ,

having no fuel and only limited repair and maintenance costs. Its water lifting capacity

of five to seven cubic meters per hour meets the irrigation requirements of most African

farmers, the majority of whom cultivate less than one hectare of land. The pump is

fabricated entirely from locally-available materials can be manufactured using welding

equipment and simple hand tools in the metal workshops commonly found in Africa .The

manufacturing, marketing and distribution campaigns of the treadle pump is carried out

through development organizations. In Ghana, an international non-governmental orga-

nization, Enterprise Works promoted the use of treadle pumps to assist farmers improve

their productivity and incomes. Treadle pump (TP) technology is widely believed to

be a pro-poor, poverty alleviating technology due to its demonstrated potential for low

cost irrigation, and suitability for small scale farming. The objective of this study is to

identify the factors that influence the adoption of TP. It also explores the links between

the adoption of TP and poverty status of small scale farmers.

2 Methodology

2.1 The Study Areas

The study was conducted in two Ghanaian regions of Ashanti and Volta. These regions

were selected because they are known to have recorded the highest rates of treadle

pump sales in Ghana. The Ashanti region recorded approximately 38% of total treadle

pump sales while the Volta region recorded 15% of the total treadle pump sales in

Ghana (EnterpriseWorks, 2004). The Ashanti Region lies in the south-central part

of Ghana occupying an area of 24,389 km2. The region falls within the Equatorial

Monsoon belt, which is characterized by two main seasons, wet and dry. The wet season

is associated with a double maxima rainfall regime from April to July (MAR=1270 mm)

and September to October (MAR=1778 mm)2. The region is well endowed with rivers

and lakes including man-made ones. Rainfed agriculture is predominantly practiced, and

is associated with the cultivation of major staples such as maize, cassava, plantain, yam

and some vegetables. Informal irrigation with the use of watering cans and buckets is

extensively practiced in the dry season for the cultivation of both exotic and indigenous

vegetables. In and around the capital city, however, vegetables are cultivated throughout

the year, particularly exotic vegetables. These include lettuce, cabbage, carrot, spring

onion, garden egg and green pepper.

The Volta Region is located in the eastern part of Ghana sharing the eastern border with

the Republic of Togo. It is the fourth largest region in Ghana, covering a surface area

of about 20,570 km2. (Ghana Statistical Services, 2002). It has a mean annual

rainfall of between 140 mm and 165 mm. The southern part of the region is located in

the dry equatorial zone, which according to Dickson (1977, p.27) is the driest climatic

zone in Ghana. Temperatures are generally high (between 26°C and 28°C) throughout

1 Treadle Pump (TP)2 MAR: Mean Annual Rainfall

52

the year. The region’s main river is the Volta, and is also served by several smaller rivers

and streams. Farming is the dominant form of land use and the main source of income

for most households in this region Duncan and Brants (2004). This is related to the

predominantly rural character of the region and the fact that the region is moderately

endowed with natural resources and fertile soils. Dry season vegetable cultivation is

widely practiced and some districts cultivate vegetables throughout the year. Rainfed

agriculture involves the cultivation of major staples including cassava, maize, rice and

yam. Cocoa and coffee are important export crops cultivated in the forest zones. Fishing

is another important income-generating activity, especially for communities along the

coastline and Lake Volta. Both exotic and indigenous vegetables are irrigated and these

include shallots, onions, okra, pepper and tomatoes.

2.2 Study Design and Data

The study was carried out primarily through a survey of 108 farmers comprising 52

adopters and 56 non-adopters of TP in the months of August and September 2005. In

obtaining the sample for the survey, a multistage sampling technique was used. First,

the districts in each of the regions with more adopters of TP were sampled using the

sales list provided by EW. In all, five districts were selected in the Volta region and seven

in the Ashanti region. Second, farmers in each selected district were stratified into two,

namely adopters of TP and non-adopters. Adopters were identified by using the sales list

and through assistance from sales agents. In some cases, farmers assisted in identifying

other users. The non-adopters of TP were distributed throughout the selected districts.

These were farmers who irrigated using the traditional water lifting devices such as

rope and bucket and/or watering cans. Third, all TP adopters who were available in

these districts were interviewed. Those who had stopped the use of the pump were

also interviewed. In sampling non-adopters, a simple random sampling technique was

used. A questionnaire was used to obtain farm and household level information from

adopters and non-adopters. The data collected from the survey was supplemented by

interviews with TP manufacturers and sales agents to distill information on the level of

local capacity for the manufacture and dissemination of the TP. It is to be noted that

the promotion of TP by EW in Ghana was only for a period of two years, only occurred

between 2002-2004; hence, because the study was conducted in 2005, it was only able

to assess the short-term impact of TP adoption in Ghana.

The data were analyzed using descriptive statistics and the Heckman’s two-stage model.

The T statistic and and chi-square statistic were used to test for significance in differences

in the socio-economic characteristics of adopters and non-adopters.

3 Analytical Framework

3.1 Factors that influence adoption of TP

The decision to adopt an agricultural technology depends on a variety of factors (Nowak

and Korsching, 1983; Wiersum, 1994; Mendola, 2005; Calatrava-Leyva et al.,

2005), including farm households’ asset bundles and socio-economic characteristics,

characteristics of the technology proposed, perception of need, and the risk bearing

53

capacity of the household. An ‘asset bundle’ comprises physical, natural, human, social

and financial assets. In this study, we hypothesize that the factors affecting treadle

pump adoption are as follows:

Physical/natural assets – The area of land under irrigation is expected to affect the

adoption decision. Farmers with less than a hectare of irrigated farm are expected to be

willing to adopt the technology since the area is within the pump’s capacity to irrigate.

The size of irrigated land cultivated depends on availability and the financial capacity

of the farm household for cultivation. It is therefore used as a proxy of the family’s

wealth status. Reliable access to water throughout the year is also considered a factor

in whether or not the TP will be adopted.

Human assets – The quality and quantity of household labor are expected to affect

adoption decisions. The quality of household labor is captured by the capacity to work

proxied by the age of farm household head, and the capacity to adopt proxied by the

level of education of household head. The quantity of household labor is captured by the

household size and the ratio of family members that are not earning an income to those

who earn (dependency ratio) and the number of household members who can assist in

operating the treadle pump (those of 15 years and above). TP adoption is expected

to have a negative relationship with the age of household head and dependency ratio;

TP adoption is expected to have a positive relationship with the level of education of

household head, household size, and household members above 15 years of age. The

gender of the household head is included to examine its impact on adoption decisions,

although no negative or positive relationships are hypothesized for this relationship.

Social assets – These are represented by membership in the farmers’ cooperative society

and frequency of extension visits. It is expected that membership in the cooperative

society and high frequency of extension visits will increase adoption. These variables are

expected to improve the adequacy of the information obtained about the pump, which

will have an impact on the adoption decision..

Financial assets – This is proxied by the farm household access to formal or informal

credit. Access to credit has remained a constraint to adopting improved technologies

in developing countries and it is expected that access to credit will affect the adoption

decision positively.

The adoption of TP technology can be analyzed by employing the logit or probit model.

To assist in testing for selectivity bias in the outcome equation, however, the Heckman

selection model was used to estimate both the adoption model and the poverty impact

model (outcome equation). The explanatory variables in the adoption model are age of

household head, years of schooling of household head, household size, household mem-

bers above 15 years, dependency ratio, irrigated land area, membership of association,

number of extension visits per year, gender, accessibility to credit, reliability of water

and region.

54

3.2 Impact on poverty status of adopters

In order to further investigate the impact of treadle pump (TP) adoption on the poverty

status of adopters, a multivariate analysis was done. To isolate the impact of TP

adoption from other intervening factors, the establishment of a counterfactual outcome

is required, as is the ability to overcome selection bias. According to Heckman and

Smith (1999), the establishment of a counterfactual outcome represents what would

have happened in the absence of project intervention. Zaini (2000) asserts that these

problems become more complicated when participants self select into the project. Due

to the difficulty of establishing an effective counterfactual situation, a control group was

used. The control group comprises non-adopters of TP. To allow for selection bias in the

assessment of the poverty impact of TP adoption, the identification variable approach

following the Heckman two stage procedure was adopted to analyze the data. Selection

bias relates to the unobservable factors which may bias the outcome on poverty due to

TP adoption. An appropriate identification variable for this two step procedure needs

to be found for the analysis. This variable has to influence adoption but not poverty.

Moreover, even if an appropriate identification variable were found, the results from the

procedure can be sensitive to the choice of this variable. Due to this limitation, the

results from the procedure need to be checked for ‘robustness’ (Zaman, 2000). This

paper adopted the ‘number of extension visits per year’ as the identification variable

that influences adoption but not poverty. The choice is dictated by the fact that an

increase in the number of extension visits increases farmers’ knowledge about the TP

and helps farmers make an informed decision as to whether or not to adopt. The impact

of extension visit on poverty will depend not only on the number of extension visits per

year but also on the quality of extension services rendered. The impact of this variable

was tested in the adoption and poverty models to verify its choice as an identification

variable.

The Heckman two stage procedure involves, first, the estimation of the adoption process

and second, the estimation of the poverty outcome. Following Zaman (2000), the

adoption equation (the first stage of the Heckman model) estimated is:

Y ∗i = σ + δXi + μi (1)

Y ∗i is a latent variable representing the propensity of a farm household i to adopt TP,

Xi is the vector of farm households’ asset endowments, household characteristics and

location variable that influence the adoption decision.

Prior to the analysis, pair wise correlation was conducted for the variables in the model

and it was found that some of the variables were highly correlated. One of each pair of

the highly correlated variables was dropped.

Employing the maximum likelihood estimation procedure, the probability of adoption is

obtained from the first stage of the Heckman two-step technique. This involves employ-

ing a probit regression to predict the probability of adoption. Using these estimates, a

variable known as the Mills ratio is obtained as follows:

λi =φ(ρ + δXi)

ϕ(ρ + δXi)(2)

55

Where φ is the density function of a standard normal variable,

ϕ is the cumulative distribution function of a standard normal distribution and

λi is the Mills ratio term

The second stage involves adding the Mills ratio to the poverty equation. The factors

that determine poverty are explicit in the literature and they include household and com-

munity characteristics. Lack of household ownership and access to assets that can be

put to productive use are important determinants of poverty (Ellis and Mdoe, 2003;

World Bank, 2000). The specific factors identified in the literature that determine

poverty include demography or human factors (e.g. household size, age and gender,

education and health) and social capital (membership in mutual support organizations);

physical capital (ownership of livestock and other productive assets); community fac-

tors (access to infrastructure and services, population density, urban-rural or regional

location; and external factors (civil strife, climate) (Benin and Mugarura, 1999).

The household and community characteristics with institutional factors hypothesized to

affect poverty are similar to those hypothesized to affect adoption. They are the age

of the household head, household size, dependency ratio, number of years of schooling

of household head, irrigated area, membership of water user or cooperative association,

the geographical location of the study area and the household TP adoption status. The

poverty status of the household is represented by its per capita income. The household

per capita income was obtained by dividing the total household income by the number

of adult equivalent in the household. The household income includes income from

irrigated farming, rainfed farming, livestock production, off-farm activities, non-farm

activities and remittances.

The poverty equation is estimated as:

Pi = β0 + β1Wi + β2Yi + β3λi + ξi (3)

Where

E(ξi) = 0

Pi is the per capita income of household i in US Dollars

Wi is a vector of farm households asset endowments, household characteristics and

location variable

Yi = is a dummy variable which is 1 for adopters and 0 for non-adopters


4.1 Socio-Economic Characteristics of TP Adopters and Non-adopters

The summary statistics of the socio-economic characteristics of adopters and non-

adopters of TP are given in Table 1. It reveals that irrigated farming is male dominated

with the percentage of males generally high in the study areas. The result also show that

the age of household head was not significantly different for adopters and non-adopters.

There is a small but significant difference in the years of schooling of the household

heads among adopters and non-adopters, with the former being more educated. The

56

Table 1: Characteristics of Adopters and Non-adopters of TP.

Characteristics Adopters Non-adopters % DifferenceT-test /χ2 value

Age of Household head 41.38 43.32 4.68 1.041

Gender of Household head Male (%) 94.23 98.21 3.98 1.200†

Years of schooling of Household head 10.63 9.30 12.51 1.801*

Household size 5.97 6.78 13.56 1.693*

Adult male above 15yrs 2.14 1.98 7.48 1.042†

Adult female above 15yrs 2.12 2.21 4.25 0.358†

Dependency ratio 0.67 0.77 14.93 1.810*

Irrigated area 0.66 0.58 1.12 1.440

Member of Association (%) 48.07 55.35 7.28 0.572†

Number of extension visits per year 4.31 2.07 51.97 2.456***

Access to credit (%) 5.76 1.78 3.98 1.091∗

*** significant at 1%, * significant at 10%, † chi-square (χ2) values

mean household size of adopters is significantly lower than that of non-adopters. There

is also higher numbers of adult males, and lower numbers of adult females in adopter

households, but these differences were not significant. The dependency ratio of non-

adopters is higher and significantly different at 10% from that of adopters. This implies

that the ratio of non-working members to those working is higher in non-adopter house-

holds. Therefore, labor availability is lower in these households when compared with

those of adopters. Adopters had higher number of extension visits per year (4.31) than

non-adopters (2.07) and the difference is significant at 1%.

4.2 Factors that influence TP adoption

The explanatory variables and summary statistics used in the adoption model are pre-

sented in Table 2.

Table 3 presents the estimated parameters and the statistically significant variables

explaining the adoption decision.

Diagnostic statistics (Table 3) showed that the model had a good fit to these variables

with chi-square test statistics significant at 1%. This shows that the explanatory vari-

ables are relevant in explaining the adoption decision. The signs of the variables also

agrees with a priori expectations, except the variable for age of the household head. The

Z test statistics reveal that three of the variables were statistically significant. These

were the dependency ratio, number of extension visits per year, and the regional dummy.

Dependency ratio has a negative relationship with the probability of adoption and is sig-

nificant at 1%. Increase in the number of non-working household members as compared

to those working infers lower labor availability for productive economic activities. This

apparently discouraged TP adoption, which requires labor for pedaling. Also, increase in

57

Table 2: Summary Statistics of the Explanatory Variables for Adoption Model.

Variables Explanation Mean Std.dev.

Age of household head inyears

Age of the household member responsible forfinal decisions on farm operations andinvestments

42.30 1.80

Year of schooling Years of formal education of the householdhead

9.94 3.89

Household3 size Total number of members of the household 6.30 0.19

Household membersabove 15 years

The total number of household members above15 years representing the adult workers in thehousehold

4.23 2.26

Dependency Ratio Ratio of non-income earning members of thehousehold to income earning members of thehousehold

0.72 0.01

Irrigated area The area of land cultivated under irrigation be-fore adoption

0.59 0.41

Membership of association Dummy variable for membership of Water UserAssociation, Farmer Cooperative Society; 1 formembers, 0 for non-members

Number of extension visit Number of visits from MoFA and EW per year 3.10 1.83

Gender Dummy variable for gender; 1 for male, 0 forfemale

Accessibility to credit Dummy for accessibility of credit from formaland/or informal sources: 1 for accessibility and0 otherwise

Reliability of water Dummy variable for availability and accessibil-ity of water all the year round; 1 for reliabilityof water, 0 otherwise

Region Dummy variable for region; 1 for Volta, 0 forAshanti

3 A household is taken as members who eat from the same pot over a 12 month period

the number of dependants in the household may reduce the household income available

for investments, thus discouraging adoption. The number of extension visits per year is

positive and significant at 5% showing that the more frequent the number of visits, the

higher the probability TP adoption. The regional dummy is significant at 5% and with

a negative sign, implying that Ashanti region has a higher probability of adoption than

58

Table 3: Factors that influence Adoption of TP using Heckman Two-Stage Model.

Variable Coefficient Standard Error Z P-value

Constant -0.261 0.724 0.361 0.717

Age 0.009 0.016 0.567 0.571

Years of schooling 0.050 0.041 1.211 0.226

Household size -0.025 0.055 -0.464 0.642

Dependency ratio -0.808*** 0.280 -2.880 0.004

Irrigated area 0.248 0.363 0.683 0.495

Membership of association -0.109 0.296 -0.370 0.711

Number of extension 0.067** 0.336 1.999 0.045

Reliability of water 0.358 0.309 1.159 0.274

Region -0.766** 0.316 -2.421 0.015

Log- likelihood -60.572

χ2 28.428

Probability of χ2 0.0081

N 108

*** significant at 1%, ** significant at 5%

the Volta region. In the Ashanti Region, there is easy access to big commercial markets

particularly for exotic vegetables, which serves as an incentive for farmers.

This study shows that the age of the household head, years of schooling, irrigated area,

and water supply reliability have positive relationships with the probability of adoption,

but are not significant. Similarly, household size and membership in associations have

negative relationships with the probability of adoption but are not significant. On the

whole, this result revealed that availability of labor and increases in number of extension

visits per year will increase the probability of adoption. In addition, there was a higher

probability of TP adoption in Ashanti as compared to the Volta region

4.2.1 Impact on poverty status

A multivariate analysis was undertaken to assess the impact of TP adoption on poverty

using the Heckman two-step procedure. Essentially, the explanatory variables include

the same household and community characteristics, as well as institutional factors, as

in the adoption model. The second step of the Heckman two-step procedure estimates

the determinants of poverty and tests for selectivity bias by incorporating the Lambda

into a linear regression. The Lambda is the inverse Mills ratio saved from the probit

equation describing adoption. The dependent variable is the log of the household per

capita income. The selection of the identification variable was tested by estimating the

determinants of poverty. The model was estimated using the number of extension visits

per year as the identification variable. Table 4 presents the coefficients in the poverty

model from both the second step of the Heckman two-step and the OLS (Ordinary Least

Squares) estimation procedures. The Lambda coefficient is negative and is not signifi-

59

cantly different from zero which indicates the absence of selectivity bias in the sample.

This means that the error terms of the adoption and poverty models are not correlated.

The robustness of the identification variable was tested using the “identification on func-

tional form” method. This involves including the identification variable in the model.

Again, the Lambda coefficient was not significant. The identification variable was also

not significant, which implies that it does not influence the per capita income of farm

households in the study area. Therefore, it is possible to judge the variable appropriate

for an identification variable. Since the results from the estimation can, however, be

sensitive to the choice of the identification variable and in the two models the Lambda

is not significant, the model can be estimated using an OLS.

Table 4: Determinants of Poverty.

Heckman second step withnumber of extensions asidentification variable

Heckman second stepand identifying onfunctional form

OLS estimation

Age -0.001 (p=0.87) -0.001 (p=0.89) -0.001 (p=0.83)

Years of schooling 0.073*** (p=0.00) 0.073*** (p=0.00) 0.072*** (p=0.00)

Household size -0.005 (p=0.78) -0.005 (p=0.77) -0.005 (p=0.78)

Dependency ratio 0.016 (p=0.85) 0.016 (p=0.86) 0.027 (p=0.76)

Irrigated area 0.739*** (p=0.00) 0.742*** (p=0.00) 0.749*** (p=0.00)

Membership ofassociation

-0.031 (p=0.74) -0.035 (p=0.71) -0.036 (p=0.71)

Number ofextensions

0.002 (p=0.87) 0.001 (p=0.91)

Reliability ofwater

-0.001 (p=0.98) -0.002 (p=0.98) 0.007 (p=0.93)

Adoption of TP 0.247** (p=0.04) 0.243** (p=0.03) 0.281*** (p=0.00)

Region -0.205* (p=0.06) -0.205* (p=0.06) -0.194* (p=0.07)

Lambda -0.012 (p=0.45) -0.011 (p=0.44)

*** significant at 1%; ** significant at 5%; * significant at 10%

The result from the OLS estimation is used to explain the model. The p values reveal

that four of the variables are statistically significant and affect household poverty. Three

of these have positive relationship with household poverty. They are; years of schooling,

irrigated area and TP adoption. The regional dummy has a negative sign. The years

of schooling of the household head is significant at 1 percent. The per capita income

will increase by 7 percent for each additional year of schooling. This implies that the

60

education of the household head had an impact on poverty. This is not surprising

because literacy enhances the capacity to adapt to change, understand new practices

and technologies, and improving a household’s productivity and income. The size of

irrigated area is positive and significant at 1 percent. A unit increase in irrigated area

leads to about 74.9 percent increase in per capita income. Increase in irrigated area will

increase farm output and incomes and thereby improve household per capita income.

The adoption of the TP is significant at 1 percent. The result shows that the TP

adoption increases per capita income by 28.1 percent relative to that of a non-adopter.

This shows that the adoption of a TP reduces poverty. This is consistent with findings

in a similar study in Malawi (Mangisoni, 2006).The regional dummy is significant at

10 percent and this implies that the per capita income of farm households in the Volta

region was 19.4 percent lower than the per capita income of those in the Ashanti region.

In sum, the increase in irrigated area has the highest impact on poverty followed by TP

adoption, and lastly the number of years of schooling. The higher per capita income of

farm households in Ashanti as compared to Volta is partly due to its better access to

markets.

4.3 Conclusion

The paper examined the factors influencing the adoption of treadle pump technology for

irrigation in two regions with the highest adoption rates in Ghana. The socio-economic

analysis reveal that irrigated farming is practiced mostly by men irrespective of adoption

status. There is no significant age differential between adopters and non-adopters of

the technology. However, there are significant differences in the number of years of

schooling, household size, dependency ratio and the number of extension visits per

year between the adopters and non-adopters. The factors influencing the probability

of adoption are the availability of labor and increase in the number of extension visits.

The probability of adoption also differed between regions. The impact of treadle pump

adoption on poverty revealed that the area cultivated under irrigation has the highest

impact on household poverty. Others are the adoption of treadle pump and the number

of years of schooling of the farmer. The impact on poverty also differed between regions

due to access to markets.

The implication of these findings is that extension visits are important to technology

adoption. Increased collaboration of private initiatives with local institutions such as

extension service could improve the reach of the technology to farmers. Increasing the

area cultivated under irrigation will reduce poverty: this suggests that assisting farmers

gain access to land close to sources of water or drilling of tubewells to improve access

to ground water will have significant impact on poverty reduction among poor farming

households. It is also important to stress that due to the capital requirement for ac-

quisition of treadle pump, targeted credit programs by formal financial institutions will

ameliorate the financial constraint. This also will improve farmers access to the treadle

pump because more farmers will be able to purchase the pump. The study shows the

need for public-private partnership in the promotion and dissemination of agricultural

technology to improve adoption rates.

61

The author acknowledges the financial support of the International Water Management

Institute (IWMI) for the study from which this paper was drawn.

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64


Volume 109, No. 1, 2008, pages 65–84

Vernacular Languages and Cultures in Rural Development:

Theoretical Discourse and Some Examples

E. Nercissians ∗1 and M. Fremerey 2

Abstract

The role of language and culture in rural development projects is investigated. Examples

taken from the context of Northern Iran, the significance of which is not confined to its

agricultural and forestry resources and extends beyond national borders, are presented.

A starting point of the analysis is an appreciation of diversity, not only in the biological,

but also in the cultural sense, as an asset and viewing development endeavors as sense

making acts. It is further argued that new intangible forms of capital are increasingly

gaining in importance in the contemporary world. Capital is considered not merely

as an asset, but as a relation having accumulation moment as well, and impact on

the regeneration of cultural and economic divides. A central concern is enhancing

social inclusion and promoting conditions for making voices of otherness heard. It is

deemed that vernacular voices encompass valuable indigenous knowledge and modes of

perception, the negligence of which can undermine the success of rural development

projects.

Keywords: language, culture, social inclusion, rural development, Iran

1 Framework

The role of language in development, despite its obvious relevance, even centrality

considering its species- specific place and its role in communication process, has so far

remained a neglected area and largely escaped scientific investigation and theorization

(Bearth, 2000). Among the studies that have constituted an exception to this rule and

have considered language as a primary topic in development research, many have been

carried out from a dominant- centric position. A major problematic in those studies has

been the language as a problem in itself: how to deal with the question of linguistic

diversity and lack of competence in a major language that can serve as the means

for common discourse and social interaction. A World Bank publication (Chiswick

et al., 1996) devoted to the economics of language exemplifies this approach. One of

the consequences of linguistic heterogeneity, according to the analysis presented in that

∗ corresponding author1 Dr. Emilia Nercissians, Department of Anthropology, Social Sciences Faculty, University of

Tehran. Iran. [email protected] Prof. Dr. Michael Fremerey, Institute for Socio-Cultural Studies (ISOS), University of Kassel.

Germany. [email protected]

65

study, is a reduction in communication among segments of the population. This is the

equivalent of an increase in transaction costs or the costs of exchange. It presents a

mathematical model of an economy and demonstrates that linguistic divisions in the

population retard economic development and exacerbate other often vexing problems,

namely, inequality, poverty and inequity in the society. Further analysis demonstrates

how microdata on individuals and households can be used to study issues related to the

determinants and labor market consequences of dominant language fluency. The obvious

conclusion is that majority language education is not only economically necessary, but

also socially desirable. It is desirable especially from the minority point of view, because

it is they who suffer from linguistic disadvantage. The study introduces the concept of

language capital; but only as a subset of human capital satisfying the triple requirements

of being embodied in the person, costly to create, and productive. The viewpoint

elaborated in the mentioned study shows the stances common to several other studies.

Not only are the recent sociolinguistic works discussing the advantages of multilingualism

and linguistic diversity not taken into account, but the newer trends in development

research appreciating diversity are also not considered. The latter trends can be seen, for

example, in recent UNESCO studies e.g. the Universal Declaration on Cultural Diversity,

adopted by the UNESCO General Conference (2001). Explicit in the declaration is that

cultural diversity is as important a factor for development as biological diversity. In

terms of intangible and oral heritage, it has been argued, the world is experiencing the

rapid disappearance of local languages and of traditional cultures and their underlying

spirituality, and of knowledge traded over generations, which is profoundly relevant for

sustainability.

Exoglossic language and educational policies inherited from the colonial era have con-

tributed to perpetuating a conceptualization where access to innovative knowledge and

hence to social and economic development and to full participation in processes of de-

mocratization and decision-making, is considered linked to proficiency, if not in English

or some colonial language, at least in a nationally or regionally dominant language. That

there is a one- way communication of innovative ideas from the developed states and

institutions to the underdeveloped or developing countries, regions, and nations, which

still carry the “burden of traditionalism”, is a common supposition reinforced by the cor-

relation of innovation and development with modernization and industrialization, which

are ultimately identified with westernization and the fact that funding flows from the

former to the latter. Even critical studies of rural development otherwise trying to adopt

minority- centric points of view and consider the role of indigenous languages in devel-

opment communication, often start from the presupposition of a development source

language, DSL, as opposed to a development target language, DTL. Outright majority-

centric stances are, of course, becoming discredited. Much emphasis is now put on

notions of participatory and endogenous development projects. That target community

should assume control over its development and orient the development plan around lo-

cal resources has become an important goal not only for progressive non- governmental

organizations, NGO’s, formed to promote that idea, but also for donor institutions as

well. The two main motivations cited are enhanced sustainability and better use of in-

66

digenous knowledge (Bearth and Fan, 2003). However, important as the emphasis on

local control may be in many respects, it is claimed that it does not go far enough, and

endogenous control of rural development does not yet guarantee a break from dominant-

centrism. In fact, whether the target economy is completely market- based, or if it still

has remnants of traditionalism, relations of dominance are often no less pronounced; and

neither is the tendency to innovate and experience helping identify the best development

path necessarily stronger. Good intentions and promising approaches may also fail to

lead to better implementations due to inadvertent methodological defects. It has been

pointed out that in many pluridisciplinary and practical research works where sociological

approaches to economic and linguistic problems are adopted, little attention is paid to

philosophical and methodological issues, and by default, the sociological analysis is con-

ducted within the theoretical confines of the dominant paradigms. Functionalist biases

are inevitable results (Nercissians, 1988b, 2002). In particular, uncritical considera-

tion of target communities as total entities and lack of regard for the heterogeneity and

internal conflicts and contradictions are important drawbacks. Another shortcoming to

be avoided is the notion of overadapted agencies and the consequent social determinism.

A new concept of glocal development has found currency in the contemporary integrated

world. Both exogenous and endogenous factors are important for rural development and

it is their interaction that leads to the selection of the proper route. Our stances are

that we should go beyond target community control of the development process and

study conditions under which social inclusion is enhanced and those voices that were

kept silent can now be heard in development communication. Even beyond that, it is

not enough to hold that increased participation, not only by the target community as

a whole, but also by its different strata, is an important condition for successful and

sustainable rural development. Social inclusion, it should be emphasized, is not a pre-

condition but an end for rural development projects. It is also important to overcome

the forces hindering development. The iron grip of dependency cannot be broken unless

raised vernacular voices other than those sustaining it are heeded.

It has been posited as a starting point for consideration of language as the missing

link in development studies, that it is not the mere comprehension of, and collective

action response to the idea of development, presumably emanating from some exogenous

source, by the target community, that should constitute the objective of development

communication. The more important question is its internalization and endogenous

reproducibility through negotiation and argumentation processes. In other words, it

is conjectured that communicative sustainability is a prerequisite to sustainability in

development. Again, this paper purports to go beyond that premise. Of course, it is

important to penetrate communal discourses on development issues, something that

is impossible unless the idea is expressed in a language that is understood by them,

even if it were true that their vernacular, and the very fact of linguistic heterogeneity,

had a detrimental impact upon the development project. But the latter supposition,

even if it could be considered true in the past, can no longer be supported by the facts

in the contemporary world. We should take several steps beyond the stance/current

status, stressing the importance of expressing the development message in the target

67

language even though it could be costly. Firstly, heterogeneity and diversity can be

an asset rather than liability. Furthermore, social creativity can enhance the value of

diversity. In sociolinguistic studies, the concept of additive multilingualism has been

elaborated for examining the conditions under which maximum benefit can be obtained

from societal plurilingualism (Nercissians, 1988a, 2002, 2004). Secondly, even if it

had no advantage, vernacular development, through being an objective of the endeavor,

should be pursued. And finally, vernacular expression of the development project, and

not its mere translation, is essential for overcoming the real obstacles hindering it.

What has been said about language is also true for culture (Hannerz, 1992). Closely

related to languages and cultures are mental structures, ideologies, norms and values,

customs and behavioral patterns, and identities. Their correspondence, however, need

not always be one to one (Nercissians, 2002; Nercissians and Lucas, 2005). Our

approach to development stems from the belief that it is closely related to the process

of sense making. Our sense of self is always correlative to our sense of an external, con-

straining reality. Biological organisms are both an embodiment and a source of meaning:

communities of fate becoming communities of will that are discursively constituted and

oriented towards freedom, transcending the intrinsic drives of the organic life towards a

future shaped by an ideal. A main concern is how ideal types or standards are formed.

The concept of multiglossia refers to the existence of several different standards, differ-

entially endowed with social prestige. Each standard is considered proper in a certain

domain. A two dimensional approach to the scientific conceptualization of diglossia

suggests that the standards are compared along different axes. The prestige or status

dimension gives rise to an overt standard that is formed from above, while the solidar-

ity or identity dimension also leads to a covert standard formed from below. The first

standard is proper in domains that are more formal, and therefore does not include the

intimate and family domains, and is thus superposed, that is, obtained through a process

of formal education. It has also been argued that the ability to compartmentalize the

domains, and freely switch between different standards is an index of social dominance.

Others find themselves in a situation where there are contradictory expectations always

co-present. They have to carry out an act of balancing. Thus they always underachieve

because if they pursue one ideal too far they fall too far behind alongside the other ideal

axis. This extended model can be as easily applied to the spheres of cultures, social

norms, and identities (Nercissians, 1988a, 1992, 2000, 2001, 2004).

The rest of the paper is organized as follows. The concept of language capital, cultural

capital, and other symbolic and intangible capitals and their role in rural development

projects is analyzed in the next section. Examples illustrating the role of vernacular

languages and cultures are provided afterwards. Concluding remarks constitute the final

section of the paper.

2 New Capitals

Rapid technological progress especially during the past decade and the advent of disrup-

tive technologies like infotech and biotech has led to radical shifts in social and economic

paradigms. An important aspect of the shift is the ascent to hegemonic position of a

68

new economic sector. The sector, which at least in some respects includes quite tradi-

tional spheres of economic activities, but in contemporary world can be called the (newly

recognized) sector of intangibles, incorporates most of the economic activities used to

denote as service sector, as well as newer activities producing knowledge and other goods

related to culture and consciousness. This new sector is growing very rapidly, employs a

large part of the workforce, is generally more productive, and exerts its influence upon

the older sectors: agriculture and industry. Computer networks and economic activities

in virtual space are reinforcing the trend towards the information- based digital economy.

Success in the new economy no longer depends only on workforce and machinery. In

the new economy knowledge and the ability to mobilize and coordinate efforts and find

best ways of dealing with physical and environmental constraints are more important

factors for increasing productivity (Lucas and Nercissians, 1987, 2003).

Social and economic changes in the contemporary world are associated with changes in

anthropological and cognitive- behavioral spheres. A major expression of those trans-

formations is the increased importance attached to representation and signification. In

a rapidly changing world where flexibility and adaptability are crucial, functions and

meanings are not considered fixed and total any more. Everything becomes a subject

for re-use, re-deployment, re-interpretation, and re-signification through denotation as

well as connotation. Cultural items, through becoming commodities, become economic

categories. But use values are no longer primary aspects of economic commodities.

Rather, goods and articles are consumed mainly because of their semiotic attributes.

Their use marks consumers’ identities. This fusion of culture and economy intensifies

the sense making process. Development plans become first and foremost endeavors to

endow community life with new meanings. Language is the most important tool for

this process of semiosis. To carry out the development plan, the community must first

accept it as its major discourse.

The construct of a learning organization (Senge, 1990) has been proposed as a suitable

tool for the conceptualization of rural development projects. Success in development,

it has been argued, will depend on organizational competencies and developmental po-

tential of the rural community. Drawing upon past and ongoing theorizations on orga-

nizational development and learning, Senge (1990) has elaborated five core disciplines

for building a learning organization. The first, personal mastery, refers to individual

community members’ learning. Organizations learn, in part, through the synergy of the

learning processes of individuals constituting them. Argyris (1993) holds that many

people and organizations practice defensive reasoning, i,e, act so as to avoid embar-

rassment or threat. But to avoid embarrassment and threat, they also avoid learning.

Effective learning, therefore, becomes possible when the flaws in mental models are dis-

covered and corrected. Team learning constitutes the third core discipline. It begins with

dialogue and builds up the capacity of individual members to suspend assumptions and

think together genuinely. Next comes shared vision. The latter can be built by finding

good compromises between individual visions and developing those visions in a common

direction. The fifth discipline is denoted as system thinking. It most of all refers to the

primacy of the whole. A learning organization is thus an entity which individuals “would

69

truly like to work within and which can thrive in a world of increasing interdependency

and change” (Senge, 1990).

The concepts of knowledge capital and social capital have in recent times been widely

used both in theoretical works and in practical feasibility analysis for development

projects (Coleman, 1988; Dasgupta and Serageldin, 2000; Putnam, 2000; Buck-

man, 2004). Closely related are the concepts of symbolic capital, language capital, and

cultural capital (Bourdieu, 1986). These constructs are somewhat more suitable for

our purposes because the term capital does not carry the implied functionalistic conno-

tation of being free of conflicts. The concept of knowledge capital draws upon theories

on intellectual capital and knowledge management. With the advent of the digital econ-

omy and the leading role of the economic sector of intangibles, there can be no doubt

about the importance of leveraging knowledge for creating value. Knowledge here is

viewed as a resource and capital refers to the value creating process. Intellectual capital

theory, according to this view, discusses intellectual endowments as the stock or content

of knowledge, while knowledge management theory is about the flow of that resource.

Unlike the activity- based view of an enterprise, which focuses on particular tasks people

carry out in the course of doing their work, the knowledge- based view elaborates the

functioning of a more responsive, learning, and intelligent enterprise in a more rapidly

changing world. A knowledge-based organization is thus closely related to a learning

organization (DiBella and Nevis, 1998; Fremerey, 2000, 2005). Both are models of

intelligent organization in a sense more general and holistic than the sum total of intelli-

gences of the people forming it. The main method for creating knowledge capital is said

to be through conversation. These are structured interactions during which the leaders,

practitioners, and stakeholders reflect upon their experiences, share understandings, and

explore the different dimensions of knowledge creation.

The construct of social capital also refers to the potential of leveraging one’s social

support for material gain. Poor and disadvantaged communities, both in urban and

rural settings, often have rich and close knit social networks, upon whose solidarity and

assistance they can count to confront poverty, hardship, and crisis, and which could be

utilized to reduce vulnerabilities, resolve disputes, share knowledge, etc. Social capital

is, therefore, a main asset for rural communities that lack other assets available to more

affluent entities. Social capital thus refers to the civic virtue embedded in a sense net-

work of reciprocal relations; it consists of the trust, mutual understanding and shared

norms, values and behaviors that binds members of the community together and make

cooperative action possible. The conjecture proposed in this paper is that even social

capital does not always mean homogeneity and total harmony. Diversity can also be an

enriching aspect in many cases that can be leveraged for more effective development.

But it does involve understanding, tolerance, and trust: that which motivates people

to commit themselves to goals and courses of action. The lack of it may not only

lead to frictions and inefficiencies that hinder development, but also to wars, massacres

and genocides that modern history of rural developments has, unfortunately, registered

so very often. When ethnicities are suppressed, expelled, or exterminated, then the

knowledge capital embodied in their cultures, languages, and customs are lost as well.

70

In many cases, ethnicities constitute the organizing principle for division of labor, and

ethnic conflicts disrupt human resource utilization processes for decades to come. There

are many examples from different times and places, including those from conflict areas

surrounding Iran. The successive massacres and genocides of Armenians, Kurds, and

other ethnicities, in eastern Anatolia, for example, has left that area undeveloped despite

favorable conditions, and is leading to larger scale, intra- state conflicts on utilization

of water resources. The Hutu-Tutsi conflicts in sub-Saharan Africa leading to the re-

cent genocide in Rwanda provides yet another example (Uvin, 1998; Pons-Vignon

and Solignac Lecomte, 2004). Degradation of lands and forests, destruction of wet-

lands and frequent flooding, loss of habitat for wildlife and sedimentation, and economic

collapse has been the result of massive suppressions, resettlements and massacres. In-

donesia provides ample examples how hegemonic and centralized rule undermines and

finally destroys locally grown modes of rural production and natural resources manage-

ment which have proved to be appropriate and sustainable (Sunito, 2003). Conflicts

are also instigated by colonialist and imperialist interests, and these can be circumvented

only by attitudes of tolerance and comradeship arising from conflict-long history of living

together and strong consciousness of community of interests.

We propose to distinguish between bonding capital and bridging capital. The former

refers to inter- group ties like kinship and language. The latter refers to strategies

promoting social inclusion. Bridging social capital refers to propensities to transcend

various social divides. A third construct, linking capital, has also been elaborated to

account for non- equal divides. Linking social capital refers to reaching out across power

and class divides. The constructs of knowledge capital and social capital have found

very wide acceptance among not only radical theoreticians but also international donor

organizations. Various means for their operationalization and quantitative assessment

have also been proposed. On the other hand, their contradictory conceptualizations

and functionalist biases have also been widely criticized. Bourdieu’s conceptualization

of social capital, however, includes a critique of functionalism. It expounds the problem

of struggle for dominance as well as the dialectic between the objective and subjective.

But even there, capital is understood mostly as a resource. Bourdieu distinguishes

economic, social, symbolic, and cultural capitals. The latter forms are capitals since

they are interchangeable with and transformable into economic capital. Central to his

theory is the concept of habitus (Bourdieu, 1986). It refers to the system of acquired

dispositions that are both categories of perception and organizing principles of action. It

functions as a regulating element in reproduction and reconstruction of social relations

and status within social space through making ideologies, and senses of social dynamism

appear self evident, masking their representational essence. Structures of dominance

are not maintained through complete functional fits or challenged due to lack of a

complete fit. Break in prevailing order, rather, can happen through removal of veils

of misrecognition. Legitimacy is conferred to social structure in the form of symbolic

capital. The social world presents itself as a symbolic system organized through the

logic of difference. Consumption of certain products and occupation of certain places,

for example, signify differences that construct social positions. It is indeed through signs

71

and signals that sense making is negotiated and meanings are constructed. Thus class

appropriation of symbols, like class appropriation of material means of production, can

lead to social divisions and reproduction of power relations. Consciousness is not mere

reflection of objective conditions, even allowing for miscognition due to distortions caused

by social interest. Production of meaning, rather, is like production of material goods.

Through symbolic capital, it is possible to engage in reconstruction of the social space

within the plurality of its possible structurings. Culture and education are the central

factors in ordering the social space and affirming class differences. The educational

system reproduces cultural division of the society. Cultural capital refers to collection

of forces that influence social status. Through acquiring cultural competence, one can

obtain social distinction. Finally language, through being the most important semiotic

system, and the most direct and species- specific means of communication, is in the

center of attention in this paper. Like the other forms of new capitals, it can be leveraged

and is an important factor in reproduction of social relations. This raises the question of

social commitment: Do we try to reaffirm our status and power? Or shouldn’t we feel

challenged to take a meta-position, which means to resort to a language which serves

as a link rather than a divide between different groups and strata?

Before elaborating examples on the role of language in rural development, let us briefly

point out three important aspects. Firstly, language constitutes a holistic mode of con-

ceptualization as demonstrated by different interpretations of the Sapir-Whorf hypothesis

(Nercissians, 2000). Secondly, language embodies local knowledge. The latter con-

cept has been the focus of much attention in recent research on rural development.

It advocates the inclusion of local voices and priorities, and promises empowerment

through participation in the process – though it rarely escaped the dominant-centrism

bias. Thirdly and most importantly, language constitutes access key to the correspond-

ing imagined community. Furthermore, research on the interface of languages can reveal

the extent of communicative reciprocity.

It was argued that capital should be differentiated from asset or factor of production.

Viewed as a process rather than an entity, it incorporates the accumulation moment.

With accumulation come social stratification, exploitation, and dominance. New capitals

are no exceptions. Their role in reproduction of existing social divides as well as creation

of new divides is as important as their potential for being leveraged for achieving better

models of rural development.

3 Examples

To illustrate the topics discussed in the previous sections, let us consider rural devel-

opment projects in north Iran. The importance of that region stems from several con-

siderations (UNIDO, 1998; Shakoori, 2001; Plusquellec, 2002; I.R. Iran, 2001,

Gilan Regional Committee on Irrigation & Drainage). Firstly, it includes the southern

coast of the Caspian Lake. The geopolitical importance of the Caspian is far greater in

scale than regional or even continental. It is the largest inland water body in the world.

Despite its long distance from the open waters, it has many characteristics for which it

is designated as the Caspian Sea. It accounts for more than 40 percent of the overall

72

volume of the world’s lacustrine waters. Its moderating role for the harsh climate of

Western Asia cannot be overestimated. The Caspian region includes steppe land in the

north, cold, continental deserts and semi-deserts in the northeast and east, and warmer

mountain and highland systems in the south and southwest. It supports very rich bio-

diversity. Over 400 species are unique to the Caspian. Its native sturgeon accounts for

approximately 90% of the world’s caviar industry. Secondly, Northern Iran is important

for its environmental conditions and economic situation. The striking contrast between

the extremely favorable climate in the coastal area in the northern parts of the country,

and the mostly desert central and southern parts is obvious to every visitor. The geolog-

ical depression of the Caspian Lake is a result of the rise of the Alborz Mountains in the

Cenozoic. With an approximate area of 60,000 square kilometers, the thinly stretched

coastal areas between Alborz Mountain range and Caspian Lake occupy 3.7 percent of

the country. In 1986, the Guilan and Mazandaran counties constituting that area had

a population of about 5.5 million, or 11 percent of the country’s total population. The

diverse topography endows the region with a beautiful natural landscape. Its forests are

the only ones in the country that have been commercially explored/exploited. It holds

40 percent of Iran’s pastures and 8.5 percent of agricultural lands. Rural development

in the coastal region is particularly important in Iran. The area is the main source of

growing rice and tea for the country, the most important attraction point for internal

as well as international tourism, historically the center of Iran’s fishing industry, as well

as many other rural activities, some also unique to that area. Another very important

factor is the existence of dense forests, unique in the country and especially important

for the very high level of air pollution that has become a major problem in recent times.

On the other side of the Alborz, the climate changes abruptly. However, the rivers

flowing from the mountains still furnish favorable conditions. Historically, the area has

always been important for the trade routes that connect Asia to the West, and for the

large cities that have served as the capital of the country in different times. Tehran,

the capital of contemporary Iran, is situated in the southwest of Damavand, the highest

peak in the country; and has been attracting migrant populations from every side of the

country. But the eastern half, which was economically very active before the Mongolian

conquests, has remained underdeveloped and under-populated; leading to the danger

of desertification. The rapid development in the rest of the region under considera-

tion during the past few decades, on the other hand, have inflicted severe damage to

the already very fragile and vulnerable environment; and will continue to inflict even

more disastrous damages, unless a carefully studied change of development course is

attempted. We shall especially focus on the more favorable environmental conditions

of the southwestern coast of the Caspian, although the danger in continuation of the

extensive trends in the development projects is more or less the same in the whole region

under consideration.

The dangers posed by continuation of the present course of development are indeed great

(Farvar and Milton, 1972; Messer, 2001; Cambers, 1998; Plusquellec, 2002;

Kashani, 2003). With the region’s geographical diversity and abundance of natural

resources, unique patterns of population settlement and spheres of business activity

73

have resulted. Its vast economic possibilities have served as a magnet for people and

the area has become quite congested with a density of 90 persons per square kilometers,

three times the national average. The absence of town planning and the exploitation of

any available property to accommodate settlers, the invasion of the natural plateau, and

congestion generated inadequacy and disruption in the activities of towns constitute

some of the main problems in those areas. A case in point is the development of

tourist facilities. Townships and private villas were hastily built along the coast between

Ramsar and Babolsar in order to accommodate more tourists. This development scenario

exposes the sensitive natural environment to misuse, misappropriation and damage, and

also creates insufficiencies and disruptions in the region. Statistics show that forest

areas which have been converted into farm lands and orchards have increased ten-fold

compared to 60 years ago and the decline in jungle coverage definitely has environmental

repercussions. Compared to figures in 1963, the total forest area has been cut down to

half, and each year, about fifty thousand hectares more are ruined.

The geographical territory of the region is characterized by a delicate balance between

marine, aquatic, and terrestrial ecosystems. The growth of populations and cities with

the inevitable increase of traffic, agriculture and industries is one of the culprits of

desertification in the Caspian Lake. Another hazard is soil erosion. This deterioration of

fertile soil results from overgrazing by sheep, cows and horses in farms and households

and from the fact that forests are cut down. Frequent sea water flooding, poor irrigation

practices and high rates of water evaporation leads to salination. Both land and water

animals and plants are adversely affected. Entire breeds are destroyed or replaced.

Migrating birds lose valuable habitat and are forced to find alternative places to feed

and breed. A build up of salts in soil, eventually to toxic levels for plants, is the

process of salination of groundwater. Salination increases risks to human health because

there are few alternative drinking water sources. Damage to coastal habitat alters land

use patterns, especially in cases of recreational activity. It reduces the aesthetic and

economic value of the land. In Iran, the rapid urbanization and industrialization of

coastal areas has not been followed by adequate construction of sanitary and solid waste

infrastructure. The resulting deficiencies are most clearly noticeable in relation to water

pollution in coastal areas, especially rivers that pass through populated and industrial

areas. The most conspicuous example of this phenomenon is the Zarjab River that

enters Anzali lagoon and carries the pollution load of numerous factories and towns into

this water body.

The main vulnerabilities identified in a study conducted by the Caspian Environment

Programme, were categorized in the following aspects. Fishstock, including sturgeon

is declining drastically. The coastal landscapes and habitats are damaged by a variety

of natural and man-made factors. Natural factors include water level fluctuations (on

both storm and decadal scales), earthquakes, and climate change. Some of the man-

made causes of the degradation of coastal landscapes and damage to coastal habitats

are: deforestation, regulation of rivers, urbanization/ industrial development, inadequate

agricultural/ aquaculture development, inadequate recreational development, and land-

based and sea-based pollution. Caspian species biodiversity across nearly all phyla is low

74

compared to that of other more open seas. Decline in environmental quality includes

the decline in air, water and sediment quality, damage to ecosystems due to human

activities, loss of aesthetic appeal, and related issues. UNDP, EU, World Bank, WHO,

and other health data sources in the region show high levels of infant mortality, rela-

tively short life spans compared to developed countries, and incidence of certain types of

diseases in certain areas. Water level fluctuation is a major threat to coastal infrastruc-

ture. Wind-induced or storm-induced surges cause considerable flooding or exposure of

coastal areas. Lack of planning at all levels has led to construction practices that ig-

nore water level fluctuations. Desertification may push urbanization closer to the water,

further increasing pressure on coastal infrastructure. Significant portions of the coasts

are located in seismic zones of magnitude ranging from 6 to 7. Earthquakes may cause

hazards due to the strong tectonic activity in the middle and southern sections of the

region. Introduction of exotic species is a recurring phenomenon in the Caspian Lake,

as much of the ecosystem arises from flora and fauna transported from other bodies of

water. More recently, man has introduced foreign species both purposely and acciden-

tally. Certain mollusks have been introduced into the North Caspian Lake in the past,

for instance, in response to changes in river hydrological regimes. Plant species have

been introduced to coastal wetlands in Iran. Some of these species have unexpectedly

caused anoxia in lagoons as a result of decreasing light penetration. A main threat is

the contamination caused by offshore oil and gas activities. Besides extraction, down-

stream activities such as oil refining, transport, and related industries also increase the

environmental pressures in the sea, in the sediments, and in air.

Rural development projects, during the past decades, have been planned and executed

with the support of a number of Iranian and international organizations. Some of the

official institutions as well as non-governmental organizations, NGO’s, are very progres-

sive in their outlook. Jahad is an example of a governmental body, though initially

set up after the Iranian revolution as a semi- official organization composed of volun-

teer workers who wanted to further revolutionary goals by helping the rural population

(Kashani, 2003). The Center for Sustainable Development, CENESTA, on the other

hand, is a non-governmental, non-profit organisation dedicated to promoting sustainable

community- and culture-based development. CENESTA works with a variety of partners,

from local communities in Iran and other countries to local and national governmen-

tal agencies, from universities and research organizations to national and international

NGOs. The UN bodies with which CENESTA and its experts entertain on-going collab-

oration include UNDP, FAO, UNICEF, UNSO, IFAD, UNCCD and the UN Secretariat.

CENESTA is the first non-governmental Organization born in Iran just after the Iranian

Revolution in 1979. Before the Revolution, it was next to impossible to register a not-

for-profit Organization in Iran even though the law gave the citizens the right to do so.

Any one who dared think of something not-for-profit was suspect. A group of citizens

getting together dedicated to a social aim? That was considered outright dangerous!

CENESTA was thus born out of the concern of a group of activist scientists and citizens

who were concerned that development in Iran as well as other parts of the Third World

needed its own patterns and models that should not be based on imitation of the West.

75

Indeed this would have been anathema to the state operating on the fundamental pre-

cept that development was Westernization itself. Both organizations have been involved

in rural development projects in the region under consideration in this paper. Among

supporters and partners are well known international donor bodies like the World Bank,

FAO, and UN; various ministries and governmental bodies from Iran and other countries;

and, especially in the case of CENESTA, other international progressive NGO’s with an

indigenous and participatory approach to development with special emphasis on local

knowledge and biodiversity.

“Integrated Participatory Production and Pest Management” is the designation of a

rural development project being carried out in North Iran by CENESTA in collabora-

tion with UNDP and GEF. This project addresses the rice crop production and pest

management in fourth northern provinces. At present rice yield is estimated at 4000

kg/hectare and potential yield can achieve 5000 kg/hectare under the Integrated Par-

ticipatory Production and Pest management (IPPPM) approach. The overall objective

of the project has been to improve food production strategies through greater farmers’

participation in problems identification, planning, implementation and monitoring to en-

sure sustainable farming system using Farmer Field School (FFS) as major tool. It can

be seen by examining the proposal as well as progress reports of the project that the

whole effort is directed towards increasing the productivity of the crops and combating

pests through educating a limited number of farmers in the course of fieldwork, with

the help of community animators and government extensions, and a larger number of

secondary farmers’ adopters directly exposed. The larger economic and environmental

issues like the reason why productivity is not high to begin with and whether increas-

ing the production of rice or other specific crops is desirable at all remains outside the

scope of the project. It can be argued, for example, that replacing wheat by rice as

the main diet in Iran is perhaps not so wise; and market liberalization through allowing

the export of more expensive Iranian rice and import of cheaper foreign rice may be a

more effective way of motivating farmers to increase their productivity and achieving

higher levels of self sufficiency at the same time. These and similar other issues are left

to be taken into consideration implicitly through the absorption of local knowledge of

the farmers via the “learning by doing” method adopted in the project. It is here that

the problems of language and culture, and the more general question of new capitals

come into the picture. In the 1st IPPPM Workshop where CENESTA experts and Jahad

staff were participating, the facilitators and participants narrated their initial hesitation

to participate in classes they did not consider relevant, their motivation to continue to

participate in order not to miss the opportunity to become experts, and their enthusi-

asm for the project realizing its respect of the farmers and the real possibility of gaining

control over the project instead of following government directives and advices. It be-

comes at once clear that language and cultural capitals, paving the way for being the

chosen participants and facilitators, can be leveraged for gaining social control. Some

speakers actually expressed their main motivation as gaining that social control rather

than achieving the project goals.

76

In order to illustrate some of the other issues associated with the role of language and

culture in rural development, let us consider the Taleshi and Tati ethnicities, which

are, in fact, the aboriginal people speaking dialects once spoken in the north, but are

now confined to few villages (Samadzade, 2002; Chizari et al., 1999; Mohseni,

2002; Ramazani, 2002; Wijayaratna, 2004). In fact, the very name of the once

widely spoken language and the corresponding ethnicity, Tat, marks otherness; since

it has been derived from the Turkish stem meaning one whose identity is other. The

choice of these ethnicities does not mean that similar analysis cannot be carried out

in the very multiethnic context of northern Iran. In fact, it is to be noted that ethnic

diversity is a characteristic of the northern part of the country. There are many different

languages spoken in that area, both aboriginal and newer ones formed as a result of

migrations especially from Central Asia that have become native languages, and the

corresponding ethnicities have been forged as a result of assimilation of aboriginals into

the migrant population. During the course of the history, the influence of invading

cultures and dynasties has reached northern areas with more difficulty and time lag and

has been successful only through assimilating the locals. Whether or not those languages

are structurally close to Farsi, the dominant language in Iran, they are all considered

vernacular and the prestige associated with any particular language reflects mainly the

dominance pattern of the corresponding ethnicity in local or regional sense. However,

the more aboriginal languages enjoy stronger support for ethnolinguistic vitality from the

solidarity dimension. The less dominant a language is, the more its speakers are excluded

from the development communication. In the case of Taleshis, they are still concentrated

in towns and villages in the very thin coastal area between Talesh Mountain range and

the Caspian Lake. Their local influence has vanished especially after the constitutional

revolution and modernization of Iran.

Taleshi identity is threatened not only by the dominance as well as direct migration of

Farsi speakers, but also, and even more so, by Guilaks from the southeast and Azer-

beijanis from the northeast. Both of these ethnic groups have been very active in the

constitutional movement and modernization of the country. In fact, their sociocultural

participation is resented by the less active Farsi speaking majority, and they are neg-

atively stereotyped especially through cruel ethnic jokes. The economic influence of

the Taleshis, as well as their nomadic culture and way of life, has taken a severe blow

especially following the curtailment of the political influence of their khans. There have

been massive immigrations into their homeland too. Those Taleshis that live in lowlands

have learned rice growing from the Guilaks and are now predominantly farmers. Animal

husbandry is, however, the main occupation of the Taleshis of the mountains. Taties,

on the other hand, are more scattered than Taleshis. Their villages are in the vicinity of

towns and villages of other ethnic and national groups in a larger area. Unlike Taleshis,

they are less hesitant to engage in trade and generally to urbanize. It can be seen that

the division of labor is an important aspect of ethnocultural maintenance.

Under the pressure of increasing population, and migration, as well as changing the

land use pattern, there is ample ground for ethnocultural conflict. Much of the friction

remains latent. But judged by the abusive language evident in ethnic web pages, mutual

77

antagonism is very strong. The environment, especially the forests, becomes the easiest

victim. For example, the conflict between farmers and nomads, which has become the

conflict between various ethnic groups, and has been made more acute by demographic

and economic pressures and natural and artificial environmental degradations, always

leads to deforestation by both farmers and nomads; not to mention migrants who cut

down trees for economic profit. This process is always evident whenever one studies

Taleshi- Tati, Taleshi- Azerbeijani, Tati- Azerbeijani, Taleshi- Guilak, Tati- Taleshi-

Azerbeijani- Guilak- Kurdish, as well as other inter-ethnic conflicts in the region.

When a language is excluded from the development communication, the outcome is not

always zero- sum, with one party gaining and the other losing. With the language come

the knowledge, and historically shaped modes of perceptualization and conceptualiza-

tion, which are lost to the detriment of all sides, as a result of not being leveraged and

utilized. The exclusion of the Taleshis, especially their more socioeconomically disad-

vantaged strata, from development communication, for example, deprive the planners

of the possibility of viewing the development project from the mindset of aboriginal

nomads. The latter tend to seek not an optimal steady state, but continual adaptation.

Sustainability assumes altogether new meaning from that outlook. Even without human

intervention, the region has very fragile environmental conditions. There is the threat

of natural disasters like flooding and earthquake, which has been responsible for taking

many lives in recent past. Being native, Taties and Taleshies have not only accumulated

much indigenous knowledge in their linguistic and cultural capitals, but also indirect and

implicit memories, unconscious codes of behavior, even emotions, about where to build

houses, what to cultivate and where, what to avoid, etc. that escape the consideration

of non- aboriginal planners. The interested researcher cannot fail to take note of the

immanent threat latent in the continuation of the present course of development, and

the very valuable insights on dealing with those threats contained in those vernacular

cultures and languages. Like a body that is already fragile, the environment cannot take

in and must reject foreign elements like very fast growth of rice plantations and tourism.

There are many published works and analyses documenting the implications of careless

use of technologies, many commissioned by the very donor organizations that are re-

sponsible for approving development projects. But when it comes to specific practices,

old mistakes tend to be repeated.

The problem of earthquakes, floods, and landslides is very important in the region under

consideration. Already the tectonic activities and the geomorphology of the region

pose serious problems. So does the balance between the marine, aquatic, and terrestrial

ecosystems, which has already been mentioned. The steepness of the coastal land makes

the situation more critical. There are many rivers and rich underground water resources.

Rice plantation is associated with high water consumption and irrigation requirements.

Rapid urbanization, construction of townships alongside highways, villas for the tourists

and summer retreat for the rich, pose additional problems associated with the waste.

Deforestation, overutilization of land, overconsumption of water resources, and changing

the land use patterns all increase these dangers. These problems are all present in the

region under consideration. Main environmental risks can be categorized into the impact

78

of natural disasters, increasing land erosion and salination, and limited availability of

healthy drinking water. The area is subject to earthquakes, landslides, mudslides and

floods. Often these natural disasters are worsened by human activities such as the use of

the mountainous areas and lowland plains for cattle grazing, deforestation, small-scale

agriculture, mining and road building. Landslides are very common where the surface

is not covered with dense vegetation. In drainage basins in the northern part of Iran, a

combination of natural and human factors has caused numerous landslides with a lot of

damage. Naturally effective factors in landslide occurrence are slope, altitude, aspect,

rainfall, land use, geology, and distance from faults, distance from old and new roads and

distance from main drainages. Careless development projects can increase these dangers.

This discourse, however, is carried out in vernaculars like Taleshi that are not heard in

the development communications. The outcome is much more serious than not having

mobilized the whole population because communicative and cognitive sustainability is

a prerequisite to economic and sociopolitical sustainability. Failing to hear vernacular

voices leads to the failure of the development planners to avail themselves of their latent

wisdom, and cosmovisions.

4 Conclusions

It has been conjectured that disregarding vernacular languages and cultures condemns

rural development projects to impoverishment. The arguments presented in this paper

attempt to go beyond the premise that it is important to deal with the problem of

cultural and linguistic diversity in order to achieve sustainability. It is held that diversity

is to be viewed as blessing and not as a problem. The central role of language and

culture can be seen when development is viewed as a sense making activity. The paper

stresses the role of new capitals in contemporary development process and discusses the

role of linguistic and cultural capitals not only as important assets to be leveraged in

rural development projects, but as social relations especially in the capital accumulation

process. Communication is a very important part of implementing the modernization

process both linguistically (the national language is not normally used at the village level)

and cognitively (dissimilar awareness). It has become evident that communication prob-

lems, and difficulties concerning consensus-building at community level, will inevitably

include disagreement among actors located at different levels of the communal networks

responsible for the promotion of development.

Research and practice provide ample evidence of the importance of human linguistic

and cultural diversity, on the one hand, and biological diversity, on the other. They

also point to the complexity of human-environment relationships on earth, and suggest

fundamental links between human languages and cultures, non-human species, and the

earth’s ecosystems. In particular, evidence is accumulating of remarkable overlaps be-

tween areas of largest biological and greatest linguistic- cultural diversity around the

world. It has been noted that models of development have been profoundly Eurocentric,

conflating development, modernization and westernization, and promoting particular

worldviews, cultures and technology- oriented rationalism. Participatory and indigenous

models of rural development are advocated instead. The notion of sustainability has

79

become an important consideration. But there is a contradiction between the modernist

progressivism of development discourse and the postmodern particularism of aspects of

sustainability. The question to be asked is what is to be developed and what is to be

sustained. This question is value ridden and answers can vary in accordance to ideology.

Vernacular languages and cultures, it is argued, encompass ideologies, modes of per-

ception, and implicit knowledge that are neglected in contemporary rural development

projects.

Interest in the contribution of indigenous knowledge to a better understanding of sus-

tainable development has been catalyzed by UN Conference on Environment and De-

velopment. UNCED highlighted the urgent need to develop mechanisms to protect the

earth’s biological diversity. An ever-growing body of research on vanishing cultures,

language endangerment, shift, and death, biodiversity loss and environment destruction

has emerged in recent years. As different worldviews and knowledge systems collide,

however, the bottom-up formula of participation will not easily marry the essentially

top-down framework of development and modernization. It will lead to a confrontation

of social actors with different epistemologies. Areas of biological diversity, such as the

earth’s remaining rain forests, are both the most poorly known to science, and those in

which biodiversity loss is most dramatic. These same areas host the world’s highest con-

centrations of linguistically and culturally diverse human groups, who have traditionally

lived in close contact with their ecological niches. The oral, rural and powerless nature

of indigenous knowledge has made it largely invisible to the development community

and to global science. Throughout the recent past, for example, women’s knowledge of

forestry, trees and firewood have been ignored. The World Conference On Sci-

ence (1999, Budapest) recommended that scientific and traditional knowledge should

be integrated into interdisciplinary projects dealing with links between culture, environ-

ment and development in areas as the conservation of biological diversity, management

of natural resources, understanding of natural hazards an mitigation of their impact.

Local communities and other relevant players should be involved in these projects.

Yet, due to a mix of historical, cultural and socio-political circumstances, the social

capital embodied in traditional community leaders should sometimes be tapped only

with great care, as much of that capital, although grounded in traditional networks of

mutual assistance and solidarity is also nested in clientelistic relations among kinship

groups of unequal social status. Women’s knowledge of their environment, for instance,

often thrives within the gendered spaces of work and gets little acknowledgement either

in modernistic or traditionalistic development discourse. Many feminist researchers have

reported on gender differences in access issues: land tenure, tree tenure; who plants

what tree or bush where and when; marital status, age of woman, types of by-product

or product utilization, the source of the seedling or planting and for commercial, cash

or household use.

A major aspect of the role of the new capitals in rural development, it is argued in

this paper, is their leveraging for reproduction of power relations in a community or

creation of new socioeconomic divides. The emergence and consolidation of small-scale,

local initiatives has been placed at the core of many current development programs, like

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the examples discussed in the previous section, and has led to a much more important

role for intermediaries, facilitators and brokers of development. These actors, mediating

between the rural population and project staff, are typically people who comprehend

the “project language”. Often, they are relatively younger persons who have migrated,

learnt the national language well, are functionally literate, but have lost touch with the

community resource base and, especially, the norms and institutions that govern it.

The issue of the relationship between the rise of the new type of intermediary and the

traditional community leaders, structures and institutions, is particularly interesting and

complex. Historically, the latter performed the role of facilitators and assured the medi-

ation between the state and the local population. The problem has also been discussed

in an FAO publication (1997), which finds that in the project framework, the mismatch

between the system of reasoning of the “development world”, imported through the

project-language, and the rural (peasant) world brings about a productive misunder-

standing which manifests itself in the emergence of intermediaries, whose competence

acquired in terms of mastering the project-language makes them real development bro-

kers, who may enter into competition with politically dominant actors at the local level.

Besides redefining power relations, languages and cultures, it has been argued in this

paper, encompass modes of thinking and understanding. This role, it is to be pointed

out, is not always conscious and explicit. It is often to be found in linguistic and cultural

routines, dominant discourses, plays, sayings, slight differences in the meanings, even

connotations of words, grammatical structures, rituals, ceremonials, and generally what

might be called the memetic pool of the community of practice. A nice illustration is

furnished by the Tati word for key money used in Taleshi bazaar. It has been argued

that the meaning of the term, due to the fact that Taleshi landlords are reluctant to

engage in trade or even construct shops in the land they lease out, is different from the

meaning commonly understood elsewhere in the country. The difference not only reflects

different communal understandings of ownership, land tenure, and appropriation, indeed

indicating differences in the whole economic and financial category of key money, but

also provides an example of legal technicality according to which the law of the country is

to be contradicted if local “orf” (common practice) so dictates; a point often neglected

by the courts.

The argument presented in this paper is that any move to take greater account of lo-

cal participation will nevertheless still continue with many of the great exclusions that

marked modernist development discourse. Social inclusion is the key to leveraging local

and global knowledge systems, promoting the notion of language as postcolonial per-

formative, of culture as difference, of sustainable development being about creating the

possibilities for being more. The advocated development paradigm is to re-contextualize

the idea of progress and the use of more advanced technologies coming from national

and international donors, and the systems of local knowledge implicit in vernacular lan-

guages and cultures, in a more inclusive framework created in the sense making process

of interaction with the environment.

81

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84


Volume 109, No. 1, 2008, pages 85–93

Interaction between Coffee (Coffea arabica L.) and Intercropped

Herbs under Field Conditions in the Sierra Norte of Puebla, Mexico

A. Pacheco Bustos ∗1, H. A. J. Pohlan 2 and M. Schulz 3

Abstract

Caffeine released from decaying seeds and leaves accumulates in a soluble form in the

soil. The compound is known to inhibit mitosis, reduce the access of nutrients and

water to surrounding plants which is one of limiting problems in intercropped coffee

plantations. The allelopathic interactions between coffee (Coffea arabica L.) and mint

(Mentha piperita L.), basil (Ocimum basilicum L.), oregano (Origanum vulgare L.) and

sage (Salvia officinalis L.) could be a diversification alternative and extra income activity

for coffee growers outside the harvest period that could cope with high levels of caffeine in

the soil. We tested the interaction of the proposed system (2004 – 2005) in rural area of

Puebla State, Mexico. The results demonstrate that intercropping sage, spearmint, basil

and oregano stimulate the plagiotropic growth of Coffea arabica plants most effectively

in young production systems, through volatile essential oils. Intercropping basil, sage,

spearmint and oregano in coffee plantations seems to be a promising approach for higher

income and increasing yield and quality production in coffee farms.

Keywords: Allelopathy, herbs, caffeine uptake, intercropping systems, mint, oregano,

sage, basil

1 Introduction

Coffee production and industry is a significant source of revenue and a source of job in

rural communities for many countries. The coffee price crisis like present day, create

social unbalances, instability and migration accelerated to urban areas (Cardenas,

2003; Pohlan, 2002, p. 386). If crisis continues, coffee growers in Latin America will

be forced to abandon their cultivations and to look for alternative activities, like illegal

crops (Torrico et al., 2005; Pohlan, 2001). Some coffee growers, that confront

the crisis, have begun to diversify with cultivation of medicinal and aromatic plants as

intercrops. Intercropped aromatic plants provide some advantages like control of weeds,

recycling of nutrients, use of unproductive areas and extra income.

∗ corresponding author1 Alex Pacheco Bustos, Rheinische Friedrich – Wilhelms Universitat Bonn, Institute for Tropical

Crops; D-50389-Wesseling, Germany [email protected] H. Jurgen Pohlan, Colegio de de la Frontera Sur, ECOSUR, Post Box. 36, 30700 Tapachula,

Chiapas, Mexico; drjpohlan@excite.; [email protected] Margot Schulz, Rheinische Friedrich – Wilhelms Universitat Bonn, Institute of Plant Molecular

Physiology and Biotechnology (IMBIO), D-53115 Bonn, Germany; [email protected]

85

Wide arrays of natural products that cause allelopathy are secondary compounds syn-

thesized by plants and microorganisms. The compounds belong to different chemical

classes such as, phenolic acids, tannins, flavonoids, terpenoids, alkaloids, steroids, and

quinons (Duke et al., 2000; Phippen and Simon, 2000; Einhellig and Leather,

1988; Chou and Waller, 1980b). Phenolics and other secondary products, including

flavonoids and antocyanins are common constituents of aromatic plants.

On the other hand, caffeine is a biologically active compound found in members of the

Rubiaceae family, e.g. Coffea arabica that contribute to allelopathic and auto toxic

effects appearing in coffee plantations (Anaya et al., 2002). Friedman and Waller

(1983) showed that caffeine inhibits mitosis in lettuce (Lactuca sativa L.) roots. As a

consequence of restricted development of young roots the access of nutrients and water

is reduced. The inhibitory effect is thought to be finally due to the ability of caffeine

to destabilize nucleic acids by intercalation. The researchers indicated that caffeine

released from decaying seeds and leaves accumulates in a soluble form in the soil and

is the major reason of auto-toxicity, one of the principal problems in coffee plantations.

Only 150-200 g of coffee dry matter has the potential to liberate 1-2 g caffeine/m2/year

in addition to other components, originating limitations in production. Waller et al.

(1986) demonstrated that caffeine applied externally was absorbed and translocated by

the root system of coffee (Coffea arabica, Bourbon variety).

The interest in aromatic plants has been generated in the last years among the planter’s

community and the actual demand of these profitable products in the international

market. Aromatic plants are profitable crops and the possibility to introduce them to

environmental conditions under coffee systems is high. In order to appraise this new

alternative and this possible interrelation with coffee, must be consider that allopathic

effects are produced by both crops and plant-plant interaction need to be defined.

The investigation included the following objectives:

• Establishment of suitable species for intercropping in a commercial production under

different seasons and determines if caffeine and other compounds released by coffee

may have a negative effect on aromatic plants.

• To evaluate if factors like long period of establishment, density, moisture, nutri-

ents availability, management of coffee plantations, age of the production system,

seasonality affect the plant- plant relationship when aromatic plants and coffee are

intercropped.

• To evaluate the participation of volatile essential oils in plant-plant relationships and

possible targets in plant physiology as growth stimulant.

2 Materials and Methods

Four species of aromatic plants and one control without herbs were tested as intercrops

in three different age coffee systems at two ecological conditions. The first named

“Providencia”, located at 20° 16’ 295 N and 97° 50’ 456 W with an altitude of 900 m

above sea level and the second named “Orquidea” located at 20° 16’, 887 N and 97°

86

45’ 600 W with an altitude of 550 m above sea level, both in rural area from Xicotepec

de Juarez, Puebla, Mexico.

The treatments were planted in-between the coffee rows. Randomized complete block

design with four repetitions of treatment per plot were established. An area of 12m2

(6m×2m) were demarked as experimental units leaving a free space among treatments

of 8m2 (4m×2m) without influence of aromatic herbs. Four weeks old plants of the

proposed species sown and propagated under homogeneous conditions were planted with

a density of 4 plants per m2, as treatments. For sampling growth variables on coffee,

four plants per treatment were marked. Two primary plagiotropic branches (10th and

20th) from the upper third of the plant canopies were tagged in each treatment unit for

periodical length measurements and number of leaves evaluation. Physiological variables

on coffee were evaluated every 2 months. Samples of coffee beans from experimental

units were collected separately and after processed dried to 10 to 12% moisture content.

No specific agronomical management was required for the herbs. Five fertilizations

were applied, the first with 500g/plant of compost (no nutritional data available) when

transplanting and after every harvest 50 g/plant of soluble commercial fertilizer (18-18-

18 Hydro). No controls on pest or diseases were made on the treatments. The coffee

plants were pruned after the first harvest (as traditional management) and fertilized

two times per year with soluble commercial product (46-15-15 Hydro). No agronomical

management was made and the control of Hypothenemus hampei Ferr., was made by

using pheromones tramps wit a density of 17 tramps/ ha.

Two factors were analyzed in the experiment:

Factor A: Influence of aromatic plants in physiological development of coffee

The following treatments were evaluated:

A1: coffee without aromatic plants

A2: coffee with Genovese basil

A3: coffee with spearmint

A4: coffee with sage

A5: coffee with oregano

Factor B: Effects of different age coffee systems on yield of aromatic plants

B1: New plot (5 years of establishment)

B2: Medium plot (10 years of establishment)

B3: Old plot (over 20 year of establishment)

Variables analyzed:

Plagiotropic growth (cm)

Vegetative growth (cm)

Appearance of new leaves

87

For the statistical analysis of data, SPSS, 11.0 was used. The data were subjected to

ANOVA and, when test F is significant, the means were compared using Tukey’s test at

95% probability.


In every allelopathic relation exists a plant (donor) that frees to the environment (at-

mosphere or rhizosphere) by a specific way, volatilization, leaching, decomposition of

residues, and root exudation (Chou, 1986) chemical compounds which are absorbed

by another plant (receptor) causing a damage or beneficial effect. The growth habit

and physiological properties of plants can differ markedly under different influence of

neighbour plants, in this case of study, growth stimulation in coffee due to volatilization

of essential oils of intercropped aromatic plants.

For the variables of plagiotropic growth in coffee under different ecological conditions an

increase in branch length when aromatics plants were intercropped was found (Figure

1).

Figure 1: Increasing of branch length in coffee (Coffea arabica L.) when intercroppingaromatic herbs.

A significant difference between control and treatments was found in Providencia farm,

during the whole year, with higher growth rate when mint, oregano, sage and basil were

intercropped. No significance difference in Orquidea farm for this variable was observed

but higher means of branch growth in coffee when oregano was intercropped elucidated

a positive stimulation of this treatment.

Stress in plants causes various physiological and biological changes, one of which is the

accumulation of reactive oxygen species in the cell. The reactive oxygen radicals are toxic

and may result in a series of injuries to plant metabolism. It damages photosynthetic

88

components, inactivates protein and enzymes, destroys cell membrane structure and

permeability by causing lipid peroxidation (Price and Hendry, 1989, 1991; Winston,

1990). Other authors suggest that many environmental stresses such as drought, salinity,

low temperature, herbicide application and cultural management (pruning), damage

plants directly or indirectly and suppress their vegetative growth (Larson, 1988; Price

and Hendry, 1989; Smirnoff, 1995; Thompson et al., 1987).

The effect on growth stimulation in C. arabica close to the intercropped herbs could be

related to the important role of volatilization of monoterpens from herb oils into the

environment and its effects on neighbour plants.

The importance of aromatic plants as natural antioxidants is well established (Dapkevi-

cious et al., 1998). As reported by Aruoma et al. (1992) rosemary and sage have highly

antioxidant properties due to the carnosic acid in their leaves. Carnosic acid is lipophilic

antioxidant that scavenges singlet oxygen, hydroxyl radicals, and lipid peroxyl radicals,

thus preventing lipid peroxidation and disruption on biological membranes. Antioxidant

activities of polyphenols from sage (Salvia officinalis L.) have been reported by Lu

and Foo (2001). In herbs like rosemary, thyme, and basil similar concentrations of

phenolic compounds were found (Zheng and Wang, 2001) supporting the hypothesis

that aromatic plants are good sources of natural antioxidants. Preliminary results clearly

indicate that antioxidant capacity of volatile essential oils and plants extracts are closely

related to the total growth of the coffee and the vegetative stage of the plants.

A significant difference for the number of new leaf was found in December 2005 in

Providencia farm for the treatments with basil, sage and oregano (Figure 2).

Figure 2: Increasing of leaf number in coffee (Coffea arabica L.) when intercroppingaromatic herbs.

89

Thus no difference were found in the other experimental unit, the average of new leaf

appearance in coffee were better for the treatments with aromatic herbs intercalated in

comparison with the control. A decrease in the development of new leaves was observed

in October in both experimental units, it coincides with the start of fructification and

constrain of nutrient availability for the vegetative growth.

The relationships between vegetative and reproductive growth in coffee are rather com-

plex and poorly understood. In most regions, rapid vegetative growth and fruit devel-

opment appear to take place at different times. Nevertheless, the positive effect on

appearance of new coffee leaves and an increase in branch length when intercropped

with aromatic species is of considerable relevance because flower buds in Arabica cof-

fee are initiated on the same wood only once (Rena et al., 1994), thus the amount

of growth produced in the current season will determine the crop yield of the following

growing season. Therefore, additional studies have to be performed to compare the yield

of coffee plants intercropped with aromatic species to that of control plants growing in

the absence of aromatic plants.

Experiment results and field observations show negative influence of caffeine accumula-

tion in soil on the production yield of basil, oregano, spearmint and sage. Sage, oregano

and basil revealed to be the less affected species in the three production systems evalu-

ated and high altitude conditions. Under plots of 10 year of coffee establishment, basil

and sage show better average of yield production in comparison with the other two

crops, thus demonstrating that they can adapt well to coffee plantations by the means

of a tolerance mechanism to the potentiality toxic effects of caffeine (Figure 3).

Figure 3: Yield production of herbs under different age coffee systems in Puebla, Mexico

0

100

200

300

400

500

600

700

800

Providencia Orquidea

basil spearmint

Providencia Orquidea Providencia Orquidea

New Plot Medium Plot Old Plot

sage oregano

data

in g

r/m

2 /cu

t

90

The negative interaction in soils with more than ten years of coffee monoculture has

been previously reported by Weinberg and Bealer (2001), due to accumulation of

soluble form of caffeine in the soil. Under old coffee system the yield production of all

species decrease and demonstrate that thus a involved mechanism to tolerate certain

levels of caffeine, higher amounts of the alkaloid in the soil can be toxic, limiting the

tested crops development. A notorious general result for all species is that they grow

better on younger fields and at higher altitudes.

Data demonstrates that caffeine acts as a negative allelochemical to aromatic plants.

Although there is a high potential of intercropping basil, sage, spearmint and oregano

between coffees rows in order to obtain extra income for the idle area, evidence on this

study indicates that age of the plots and accumulation of caffeine in the soil are limiting

factors in the yield of aromatic plants.

According to the available data, an estimation of production for the three different sys-

tems shows a decrease in yield with increasing age of the plot. Low altitude conditions

are not suitable for sage, oregano, basil and mint. A possible ability of the aromatic

plants to grow better under high altitude conditions may be associated with the tem-

perature and water availability.

For coffee production systems between 5 and 10 years of establishment, an extra income

of 400-500 kg of basil, sage and oregano can be obtained per cut. Three cuts during no

harvest period can be done, obtaining 1500 kg/ ha-1 as extra income for coffee growers

in crisis. The production of spearmint is not significant, and cannot compete with

commercial production, but competition with weeds and coverage in between coffee rows

open an interesting sustainable alternative for weed management in coffee production

systems.

4 Conclusions

Intercropping sage, spearmint, basil and oregano stimulate the plagiotropic growth of

Coffea arabica plants most effectively in young production systems. Coffee growers can

stabilize their income and their social condition by offering aromatic plants produced

during the no-harvest period of coffee to the local markets and using idle space of

their farms. Therefore, additional studies have to be performed to compare yields of

aromatic species under different coffee production systems. There are indications that

these herbs cope with high caffeine levels and are even able to stimulate coffee growth.

Further research of the biochemical nature of this interaction is promising and needed.

On the basis that stimulatory effect of the constituents of the evaluated volatile essential

oils acts as growth stimulants, it might be necessary to define from the qualitative and

quantitative composition the effect of each compound.

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93

94


Volume 109, No. 1, 2008, pages 95–108

Decomposition of Organic Substrates and their Effect on

Mungbean Growth in Two Soils of the Mekong Delta

M. Becker ∗1, F. Asch 2, N. H. Chiem 3, D. V. Ni 3, E. Saleh 1, K. V. Tanh 3 and

T. K. Tinh 3

Abstract

Agricultural land use in the Mekong Delta of Vietnam is dominated by intensive irrigated

rice cropping systems on both alluvial and acid sulfate soils. A stagnating and occa-

sionally declining productivity may be linked on the alluvial soils to low N use efficiency

and low soil organic matter content while on acid sulfate soils to acidity, Al toxicity and

P deficiency. For economic reasons, farmers increasingly diversify their cropping system

by replacing the dry season rice by high-value horticultural crops grown under upland

conditions. However, upland cropping is likely to further exacerbate the soil-related

problems. Organic substrates from decentralized waste and waste water management

are widely available and may help to alleviate the reported soil problems. During the

dry season of 2003/2004, the effect of the application of various types and rates of

locally available waste products on crop performance was evaluated at both an alluvial

and an acid sulfate soil site. The C and N mineralization dynamics of nine organic

substrates from waste and waste water treatment were determined by anaerobic (N)

and aerobic (C) incubation in the laboratory. The response of 12 week-old mungbean

(dry matter accumulation) to substrate application (1.5 – 6.0 Mg ha−1) was evaluated

on a degraded alluvial and on an acid sulfate soil. In the alluvial soil, largest mineral-

ization rates were observed from anaerobic sludge. Biomass increases in 12 week-old

mungbean ranged from 25-98% above the unfertilized control. In the acid sulfate soil,

highest net-N release rates were observed from aerobic composts with high P content.

Mungbean biomass was related to soil pH and exchangeable Al3+ and was highest with

the application of aerobic composts. We conclude that the use of organic substrates in

the rice-based systems of the Mekong Delta needs to be soil specific.

Keywords: acid sulfate soil, Al toxicity, N mineralization, Vietnam, Vigna radiata

∗ corresponding author1 Prof. Dr. Mathias Becker, Institute for Crop Science and Resource Conservation, Department

of Plant Nutrition, University of Bonn, Karlrobert-Kreiten Str. 13, 53115 Bonn, Germany,e-mail: [email protected]

2 Prof. Dr. Folkard Asch, Institute of Crop Production and Agroecology in the Tropics andSubtropics, University of Hohenheim, Germany

3 Dr. Nguyen Huu Chiem, D. V. Ni, K. V. Tanh and T. K. Tinh, University of Cantho, CanthoCity, Vietnam

95

1 Introduction

In Vietnam, the area planted to rice increased from 5.6 Mha in 1980 to 7.7 Mha in 2000,

with >90% of the production occurring in lowland ecosystems (Maclean et al., 2002;

Can, 2003). Nearly half of this lowland rice is produced in the Mekong Delta, where the

area cultivated with rice has been substantially increasing as a result of infrastructure

development and recent demographic growth (Chiem, 1994). Being the key component

of agricultural land use, rice is used in diverse production systems and cropping patterns.

This diversity is largely determined by soil type with acid sulfate soils and alluvial soils

covering each about 40% of the land area (van Bo et al., 2002).

Rice triple cropping systems are mainly found in areas with alluvial soils with a limited

influence of the late season flood (nearly 0.9 Mha). Fields are fully irrigated, rice is direct

wet-seeded, and production is based on high external input use. Main problems in this

production system are associated with pollution of the environment by agrochemicals and

a relatively low productivity, probably linked to near-permanent soil flooding, increased

incidence of soil-born diseases, a low N use efficiency and, in some instances, a low soil

nutrient supply and declining soil organic matter content (Dobermann et al., 2002).

With the rapid economic development in the Mekong Delta, farmers tend to diversify

their cropping system. The most prominent strategy is the replacement of the dry season

rice by high-value horticultural crops grown under upland conditions (e.g.; the rice -

rice - field vegetable rotation). While short-term economic benefits are obvious, upland

cropping is likely to further accelerate the mineralization of soil organic matter and hence

to exacerbate the problems of low soil nutrient supply and the physical degradation of

the soil structure, related to low soil organic matter content.

The rice double cropping system dominates on the acid sulfate soils and is concentrated

in areas where seasonal floods occur (about 0.7 Mha). During the period of intense

flooding in October-November, a 2-3 months fallow period follows a crop of transplanted

wet season rice. Another irrigated rice crop is grown after flood recession during the dry

season (Ni, 2000). Rice production is constraint by soil-related nutrient imbalances such

as iron toxicity and P and Zn deficiencies (Tinh et al., 2001). During intermittent soil

aeration phases, the acidification of the aerobic soil can result in severe Al toxicity and

further exacerbate the problem of P deficiency (Husson et al., 2000). The geochemistry

of the acid sulfate soils tends to limit the choice of crops to be grown during the aerobic

soil phase to the relatively acidity-tolerant species and cultivars (Minh, 1996). However,

as in the triple cropping system, mixed production of wet season rice with diverse dry

season upland crops on raised beds are emerging, particularly in the peri-urban areas.

Organic substrates from decentralized waste or wastewater treatment are widely available

in South Vietnam (Watanabe, 2003). Their use in agriculture can recycle substantial

amounts of nutrients, thus improving soil fertility and increasing rice yield (Clemens

and Minh, 2005). However, high transport costs and an unfavorable cost-benefit ratio

are limiting the use of organic substrates to lowland rice. In addition, the application

of organic waste to flooded fields may lead to increased water pollution and microbial

contamination from the substrates (Rechenburg and Herbst, 2006). When applied

96

to an upland crop grown in rotation with rice, the use of organic substrates may be en-

vironmentally safer than in lowland fields, and the substrates may contribute to alleviate

the prevailing soil-related problems.

We hypothesize that in the rice triple cropping systems on alluvial soils, the replacement

of the dry season rice with an upland crop combined with the application of organic

substrates can overcome the problem of declining soil fertility and may improve the

system’s productivity. In the rice double cropping system on acid sulfate soils, the

application of organic substrates to upland crops may counteract negative effects of

low pH and excess Al3+ and permit the cultivation of more acidity-sensitive higher-

value crops such as mungbean (Vigna radiata L.). Direct and residual effects of organic

amendments are likely to depend on the quality and quantity of the substrate applied as

well as on the type of upland crop. Accordingly, the following objectives were addressed

in both degraded alluvial and acid sulfate soils:

(1) Physico-chemical and mineralization characteristics of major organic substrates of

the Mekong Delta;

(2) Quantification of substrate effects on the biomass accumulation of mungbean grown

in rotation with rice.

2 Material and Methods

2.1 Study sites

All experiments were conducted in Cantho province of the central Mekong Delta. The

area is characterized by a monsoon climate. The length of the growing period for rainfed

crops is in excess of 320 days. According to the FAO (1978), the area is classified as

a humid forest agroecological zone. The mean annual rainfall ranges from 1,900 to

2,300 mm, falling mainly during the 6 months of summer monsoon (May-October).

Three farmers’ fields representing the triple cropping situation were selected close to

the village of An Binh (105°43’40” – 105°43’45” E latitude and 10°00’05” – 10°00’10”N longitude). Three further farms, representing the rice double cropping pattern, were

selected close to the village of Hoa An (108°0’00” – 108°5’00” E latitude and 10°65’00”– 10°70’00” N longitude). While An Binh was characterized by an alluvial clay soil with

low organic carbon and total N contents, the Hoa An site was characterized by a typical

acid sulfate soil with low available P and a high acidification potential under aerobic

conditions. Selected physico-chemical properties of the experimental soils are shown in

Table 1.

2.2 Crop plants

The widely grown improved semi-dwarf lowland rice (Oryza sativa L.) variety VD 20 with

105-day growth duration was obtained from Cuu Long Rice Research Station, Omon,

Vietnam. For homogenizing the field sites, it was pre-germinated for two days and

broadcast-seeded at a rate of 120 kg ha−1 into the water-saturated lowland field (An

Binh) or seeded into a wet bed and transplanted at 21 days after seeding at two seedlings

per hill at a 20×20 cm spacing (Hoa An). Mungbean (Vigna radiata L.) is commonly

97

Table 1: Selected physico-chemical properties of the experimental soils (0-20 cm)

ParameterAlluvial soil(An Binh)

Acid sulfate soil(An Binh)

Soil type (USDA) Tropaquept Sulphaquent

Texture Silty clay Clay Loam

Clay (%) 57 44

Silt (%) 34 55

Sand (%) 9 1

pH (H2O) 5.0 3.4

org. C (%) ∗ 1.52 4.59

Exch. Al3+ (mg 100g−1) † – 37.2

Tot. N (%) ‡ 0.16 0.26

Avail. P (mg kg−1) § 5.81 1.90

Exch. K (mg kg−1) ¶ 7.58 38.9

∗ Walkley-Black, † NaF titration, ‡ Kjeldahl, § Bray-I, ¶ NH4O-Ac extraction

cultivated in the Mekong Delta and was selected as a substitute of the dry season rice

crop. Seeds were obtained from the College of Agriculture, Cantho University. The

material was seeded at a 20×40cm spacing onto 10 cm high raised soil beds of 1×5 m,

that were constructed in the lowland plots after the harvest of wet season rice.

2.3 Substrates

Organic substrates from decentralized waste and wastewater treatment, commonly ap-

plied to field and garden crops in the Mekong Delta, were collected from farms in the

study area. These organic amendments included five aerobic substrates (vermicompost

from pig and goat manure, pig manure – rice straw compost, biogas sludge compost,

rice straw compost, and rice mushroom compost) and three anaerobic substrates (young

biogas sludge [<4 months], old biogas sludge [>12 months], and fish pond residue [30

– 50 mm depth of deposit]). The substrates differed widely in their N content (1.6 –

3%), C/N ratio (12 - 23), and P (0.15 – 1.65%) and K content (0.28–1.98‰). Selected

physico-chemical parameters of the organic amendments are presented in Table 2.

2.4 Chemical analyses

The C mineralization was determined by weight loss from litterbags containing 3 g

substrates. The organic substrates were placed into Nylon mesh bags (0.2 mm) and

incubated in the dark in three replicates per soil type (about 30 g substrate kg−1 soil)

for a period of 12 weeks (Okalembo et al., 2002). Soils were kept under aerobic

conditions at about 75% field capacity. The weight loss of the substrate in the litter

bags (dry matter) was recorded after removal, careful washing in distilled water and

oven drying for 48 hours at 70°C.

98

Table 2: Selected physico-chemical properties of the organic substrates used in thefield experiments on alluvial and acid sulfate soils in the Mekong Delta in2003/2004.

SubstrateMoisturecont. (%)

NH+4 -N

(mg kg−1)

NO−3 -N

(mg kg−1)

Total N(%)

C/Nratio

Total P(%)

C/Pratio

Total K(‰)

C/Kratio

Aerobic Substrates

Vermicompost(pig / goat)

60.4 1.40 844 2.20 19 1.39 30 0.92 454

Pig manurestraw compost

56.0 1.84 940 2.60 16 1.65 25 1.98 209

Biogas sludgecompost

38.7 2.68 1832 1.95 20 0.60 71 0.57 737

Rice strawcompost

68,7 4.28 19 1.95 22 0.15 274 0.57 732

Mushroomcompost

70.1 4.84 575 2.45 17 0.22 190 1.54 273

Anaerobic substrates

Biogas sludge (>12 months)

82.5 1.23 t 2.55 12 0.68 53 0.65 470

Biogas sludge (<4 months)

86.3 1.56 t 2.38 14 0.80 42 0.31 397

Fishpond residue(3 – 5 cm)

78.9 1.76 t 1.35 18 0.40 48 1.81 106

t: traces

The N mineralization potential of substrates applied to the two soils was determined

by net ammonium-N release during two weeks of anaerobic incubation (Stanford

and Smith, 1972). Substrates were applied at 100 mg N kg−1 soil and 20 g of soil-

substrate mixture were placed in 50mL test tubes, filled with 30mL of distilled water.

Three replicates of each organic substrate and soil type (2 soils × 11 treatments ×2 extraction times × 3 replications = 132 tubes) were incubated in the dark at 30 –

32 °C for 21 days and extracted with 2 N KCl after 7 days (initial value) and after

two further weeks of anaerobic incubation. The ammonium content in the extract was

determined colorimetrically via flow injection analysis. The net-N mineralization was

computed as (Nmin after 1 and 2 weeks of incubation) – (Nmin in the initial sample).

Substrate mineralization was calculated as the net-N release in amended minus that in

unamended sample tubes.

The total N in soil samples and in the biomass of 12 week-old mungbean was determined

by Kjeldahl method. Soil exchangeable K was extracted with NH4O-Ac, followed by

flame photometer determination. Soil P was determined according to the Bray-I proce-

dure and determined spectrophotometerically after vanadate coloration. Soil pH, total

acidity, and exchangeable Al+3 were based on a soil: extractant ratio of 1:5 (pH-H2O

). Soil total acidity and exchangeable Al+3 were determined only in the acid sulfate

soil. Soil samples (0-10 cm) were taken from individual planting holes of the test crops

99

extracted with 2N KCl and subsequently titrated with NaOH and NaF for total acidity

and exchangeable Al3+, respectively (McLean, 1965).

2.5 Treatment application

Dry season field experiments were conducted at each of the two study sites during the

dry season of 2003/2004, following the field homogenization with an unfertilized crop

of lowland rice during the 2003 wet season. In addition, experiments were conducted

under controlled conditions in the laboratory of the Institute of Technology at Cantho

University (substrate C and N mineralization). The field experiments were established

at both the Hoa An (acid sulfate soil) and An Binh (alluvial soil) sites. Three adjacent

farms were used as replications at each site with treatments being randomized within

the farms (Randomized Complete Block Design - RCBD). The experimental area at

each site was 1500 m2 (500 m2 per farm), on which 10cm high soil ridges of 5.0 × 1.0

m were built after the harvest of wet season rice in November 2003 for the cultivation

of upland crops.

Field experiments studied (1) the response of mungbean to different substrates at one

substrate application rate and (2) the response of mungbean to one substrate at different

application rates. Twelve weeks after seeding of mungbeans, the dry matter accumu-

lation was determined from 1×3m harvest areas (alluvial soil) or from individual plants

(acid sulfate soil) after oven drying at 70°C for 48 hours. Experiment 1 : The differential

effect of organic amendments on a test crop of mungbean (involved the application and

manual incorporation (0-0.1 m) of eight substrates (Table 2) at a rate of 3 Mg ha−1

(dry matter basis) in comparison to an unamended control. Experiment 2 : The effect

of different application rates on a test crop of mungbean focused solely on the “old”

biogas sludge, applied at rates of 0, 1.5, 3.0, 4.5, and 6.0 Mg ha−1 (dry matter basis).

2.6 Data analysis

Data were analyzed for basic statistics (means and standard errors) by Microsoft EX-

CEL and subsequently subjected to ANOVA using SPSS 11.5. Mean separation was

done by Tuckey Test at 5% error probability. Graphical presentations were made with

SIGMAPLOT 5.3.

3 Results

3.1 Substrate mineralization

The substrates from waste and wastewater treatment were characterized based on

physico-chemical parameters (Table 2) and on their C and N mineralization charac-

teristics in both experimental soils (Figure 1). The C mineralization (weight loss) of

soil-applied substrates tended to be generally lower in the acid sulfate than in the al-

luvial soil. In general, larger mineralization rates were observed from anaerobic sludge

than from the aerobic composts. In the alluvial soil, the aerobic C mineralization varied

between 8 and 35% weight loss. Rice straw compost showed the lowest (9-15%), young

biogas sludge the highest C mineralization (24-35% weight loss). Vice versa, the sub-

100

Figure 1: Carbon mineralization (% weight loss in litterbags during 12 weeks of aerobicincubation – upper graph) and net-N mineralization (NH4-N in amendedminus unamended soil during 2 weeks of anaerobic incubation – lower graph)of organic substrates applied to an alluvial soil – left side, and an acid sulfatesoil – right side (incubation experiments under controlled conditions). Barspresent standard errors of the mean (n=3); value bars with the same letterare not significantly different by Tuckey Test (0.05).

0

5

10

15

20

25

30

35

40

0

5

10

15

20

25

30

35

40

-3

-2

-1

0

1

2

3

4

5

6

7

8

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

bd b c d c d bc e d bc a b a a de a de d f e b d ab b c

RSC

T

PMRC

VC

PG

BSC

6

RSC

T

MRC

T

e d c d c d c a bc a b d cd c b bc b e

bd b cd e d ab a b a d ab b cbd b c d c d bc e d bc a b a b d ab b c

e d cd cd c b a bc a b d cd c b bc b e

bd b cd e d ab a bc de d bc

PMRC = Pig manure rice straw compostVCGT = Vermicompost from goat manureBSC6 = Biogas sludge compostRSCT = Rice straw compostMRCT = Mushroom compostBSC12 = Biogas sludge (12 month)BS04 = Biogas sludge (4 month)FPRS = Fish pond residues

Alluvial soil Acid sulphate soil

Car

bon

min

eral

izat

ion

(% w

eigh

t los

s)

BS12

BS04

FPRS

PMRC

VC

PG

BSC

6

RSC

T

MRC

T

BS12

BS04

FPRS

PMRC

VC

PG

BSC

6

RSC

T

MRC

T

BS12

BS04

FPRS

PMRC

VC

PG

BSC

6

RSC

T

MRC

T

BS12

BS04

FPRS

Net

N m

iner

aliz

atio

n (m

g N

H4+

- N

kg

-1)

Aerobic substrates Anaerobic substr. Aerobic substrates Anaerobic substr.

a a ab

101

strates with highest P content tended to mineralize more rapidly than the substrates low

in P in the acid sulfate soil (up to 25% weight loss in pig manure-rice straw compost).

In the alluvial soil, anaerobic net-N mineralization varied between 1.2 and 7.2 mg N kg−1

soil. It followed a similar pattern as the aerobic C mineralization, whereby rice straw

compost showed the lowest, young biogas sludge the highest net-N mineralization. In

contrast to the alluvial soil, substrate N mineralization in the acid sulfate soil was by one

order of magnitude lower. Highest net-N release was observed from aerobic substrates,

particularly those with high P content (e.g., vermicompost and pig manure compost).

Lowest N mineralization was observed with rice straw compost with –2.8 mg kg−1 soil

(net-N immobilization).

3.2 Effects of substrates application to an alluvial soil

In experiment 1, all substrates were applied at 3 Mg ha−1 to soil ridges build in the paddy

fields after the harvest of wet season rice. The biomass accumulation of mungbean

after 12 weeks of growth responded differentially to substrate application (Table 3).

Incorporation of biogas sludge resulted in the largest mungbean biomass (3.9 - 4.8

Mg ha−1). The low-quality substrates, such as the aerobic rice straw compost, the

compost from rice mushroom production and the anaerobic fishpond residue resulted in

a low and not significant mungbean response (dry matter of 1.6-2 Mg ha−1). Biomass

response and crop nutrient uptake correlated significantly with the amount of added

P (P<0.01) and N (P<0.05) but showed little apparent relation to other substrate

attributes. Increasing the application rates of young biogas sludge (experiment 2),

resulted in N additions of 0 - 144 kg ha−1, corresponding to P additions of 0 - 48

kg ha−1. While N and P accumulation in the biomass increased nearly linearly with

increasing substrate application rates, no significant differences were observed in the dry

biomass accumulation of mungbean at application rates beyond 3.0 Mg ha−1.

3.3 Effects of substrate application on the acid sulfate soil

During the aerobic soil phase (dry season), the field site was characterized by a large

and small-scale heterogeneity in soil pH (2.8-4.3), total acidity (3-23 cmol kg−1) and ex-

changeable Al3+ (7-18 cmol kg−1). Based on the analysis of 264 individual soil samples,

significant linear correlations were observed between pH and total acidity (r2=0.64***)

and between total acidity and exchangeable Al3+ (r2=0.59***) (date not shown). As

crop growth strongly responded to aluminum, the soil exchangeable Al3+ was used as

a covariate in the statistical analysis and data are presented as dry matter per plant

in relation to the exchangeable Al3+ in the rhizosphere soil (soil collected from the

individual planting holes before treatment application).

In experiment 1, eight aerobic and three anaerobic substrates were applied to mungbean

at a rate of 3 Mg ha−1. Mean biomass accumulation did not differ between treatments.

However when using soil Al3+ as a covariant, the application of the aerobically com-

posted substrates resulted in significantly more biomass than the unamended control.

Anaerobic substrates produced an intermediate response, which was not significantly

different from either the unamended control or the application of aerobic substrates

102

Table 3: Nutrient addition by substrates and the response in dry matter accumulationand nutrient uptake of 12 week-old mungbean plants to the application oforganic substrates at 3 Mg ha−1 and to increasing application rates of biogassludge on an alluvial soil (An Binh, Vietnam, 2004).

Amount of nutrient added(kg ha-1)

Mungbean nutrient contentat harvest (%)

SubstrateN P K

Mungbeandry matter(Mg ha-1) N P K

Unamended control 0 0 0 1.58e 1.40d 0.31e 1.74a

Aerobic substrates

Vermicompost 88.5 9.0 4.1 4.01c 1.28e 0.38c 1.31c

Pig manure compost 78.0 49.5 5.9 4.81ab 1.20g 0.49a 1.33c

Biogas sludge compost 55.5 18.0 1.7 3.92d 1.24e 0.40bc 1.28d

Rice straw compost 62.5 4.8 1.8 2.50e 1.02fg 0.27f 1.34c

Mushroom compost 53.5 6.6 4.4 2.04e 1.34de 0.41a 1.27d

Anaerobic substrates

Biogas sludge (<4 months) 86.5 20.4 1.5 4.81a 1.62d 0.47b 1.79a

Biogas sludge (>12 months) 72.0 24.0 1.1 3.68cd 2.18a 0.46b 1.58b

Fishpond residue 48.0 12.0 5.4 1.57e 1.06fg 0.47b 1.52b

Increasing rates of biogas sludge

0 Mg ha−1 0 0 0 1.58e 1.42d 0.31e 1.74a

1.5 Mg ha−1 36.0 12.0 0.4 3.11d 1.06f 0.33d 1.12d

3.0 Mg ha−1 72.0 24.0 0.8 3.68cd 1.52b 0.35cd 1.08f

4.5 Mg ha−1 108.0 36.0 1.3 4.21bc 1.60b 0.33de 0.97f

6.0 Mg ha−1 144.0 48.0 1.7 4.40bc 1.55f 0.38cd 1.19de

Values followed by the same letter in a column are not significantly different by Tuckey Test (0.05)

(Figure 2). In the absence of substrate application (control treatment), the mungbean

did not grow when the soil exchangeable Al3+ exceeded 11 cmol kg−1, and a maximum

biomass of 6 g plant-1 was observed with Al3+concentrations of <9 cmol kg−1. With

the addition of 3 Mg ha−1 of aerobically composted organic substrates, the critical Al3+

value for mungbean growth increased from 11 up to 15 cmol kg−1 and the dry matter

accumulation reached a maximum of 14 g plant-1 at 9 cmol Al3+ (Figure 2). The

strongest growth response (and highest Al3+ tolerance) was observed with the applica-

tion of well-rotten substrates with a wide C/N-ratio and high P concentrations (e.g.,

pig manure compost).

The growth of mungbean responded to increasing application rates of biogas sludge

(test substrate in experiment 2) and shifted the critical aluminum concentration for

mungbean growth from 11 (control) over 13 (3 Mg sludge ha−1) to 15 cmol kg−1 (6 Mg

sludge ha−1), while increasing the maximal plant biomass at 10 cmol Al3+ kg−1 from 2 g

(unamended control) to 12 g (data not shown). A comparison of the regression equations

showed no significant differences of the slopes, while the X-axis intercept (critical Al

concentration) shifted from 11 to 15 cmol Al3+ kg−1 with substrate amendments.

103

Figure 2: Mungbean response (dry matter accumulation of 12 week-old plants) to the

application of 3 Mg ha−1 of biogas sludge or of of pig manure compost inrelation to soil exchangeable Al3+ on an acid sulfate soil (dry season, HoaAn, Vietnam, 2004).

0

2

4

6

8

10

12

14

16

8 10 12 141 6

Mungbean biomass (g plant

3+ -1

Unamended controlBiogas sludgPig manure compost

0

2

4

6

8

10

12

14

16

8 10 12 14 16

-1 )

Exchangeable aluminium -1(cmol Al kg )3+

e

4 Discussion

Stagnating long-term yield trends in intensified rice-based cropping systems have been

reported throughout Asia (Cassman et al., 1997; Dawe et al., 2000; Regmi et al.,

2002) and changes in soil organic matter quality under constant soil anaerobiosis and

a declining soil N and P supplying capacity have been identified as the main culprits

(Dobermann et al., 2000; Ladha et al., 2003). Breaking the cycle of permanent soil

flooding by replacement of dry season rice with upland crops and in increased addition of

organic substrates have been hypothesized to counteract the yield decline (Dawe et al.,

2003; Ladha et al., 2003). The present work focused solely on the effect of substrate

application on mungbean grown in rotation with rice. Nevertheless, the alleviating effects

of various substrates on soil-related problems may also have positive carry-over effects

on the subsequent crop of rice and the cropping system at large. In this context, the

following chapters will discuss the decomposition dynamics and yield effects of organic

amendments.

104

4.1 Substrate mineralization

Organic substrates contain besides a range of C sources, variable quantities of essential

nutrient elements, salts, and heavy metals. However, the organic amendments need

to undergo microbial decomposition before these elements can become plant available.

Mineralization processes and rates are affected by temperature and moisture, microbial

activity, soil texture, and substrates properties such as C/N ratio, content of lignin

and polyphenols, and the lignin-to-N ratio (Palm and Sanchez, 1991; Becker and

Ladha, 1997; Dendooven et al., 1998; Calderon et al., 2004). In the present study,

soil texture and moisture conditions among the study sites were similar, while pH and the

availability of P strongly differed between the alluvial and the acid sulphate soil. Hence,

soil acidity and P limitations were likely to have been responsible for lower C and N

mineralization at the Hoa An than the An Binh site. This appears to be confirmed by the

observed high substrate mineralization rates of the P-rich pig manure-based substrates

at Hoa An. In this acid sulphate soil, substrate decomposition may have been inhibited

by soil acidity and possibly by P precipitation with soluble Al3+ and Fe. Consequently,

the N mineralization of substrates was apparently related to the C/P rather than to

the C/N ratio, as previously reported by Whalen et al. (2000). From the present

data we conclude that the C/N and the C/P ratio may be the key drivers of substrate

mineralization in the alluvial and the acid sulphate soil, respectively.

4.2 Soil and crop effects of organic amendments

Irrespective of the site, soil type or substrate, organic amendments generally improved

the performance of mungbean. This may have been related to the direct addition of

limiting plant nutrients and/or to a possible indirect effect via an alleviation of (H+ and

Al3+) toxicities. On the acid sulphate soil, acidification and Al toxicity are likely to

have further exacerbated the prevailing problem of P deficiency (Ren et al., 2004). The

extent of the ameliorative effects of organic amendments on P deficiency and Al toxicity

depended on both the amount and the quality of the substrate. Similar to the substrate

mineralization patterns, direct effects on crop biomass were related to N additions in

the alluvial and to P addition and Al toxicity alleviation in the acid sulphate soil. The

latter effects were much more pronounced with aerobic (compost) than with anaerobic

(sludge) substrates. This may be related to a larger share of stable, non-soluble C-

compounds in the composts, which can reportedly immobilise toxic Al3+ by forming

non-toxic Al–DOM complexes (Hue and Licudine, 1999) or humic complexes with

Al and Fe ions (Iyamuremye et al., 1996). While the application of lime can rapidly

correct the prevailing soil pH-related constraints, lime is currently hardly available in

the Mekong Delta and not affordable to low-input farmers. Organic substrates on the

other hand are widely available on farm and may thus provide a short-term alternative

to alleviate Al toxicity and nutrient deficiency problems.

On the alluvial soil, the pronounced effect of substrate application on the biomass

yield of mungbean was not only related to P but also to the amount of added N

(P<0.01), which may surprise in the light of mungbean being a nitrogen-fixing legume.

Nevertheless, fixation rates were probably very low and few effective (red) nodules were

105

found, possibly related to the heavy soil texture, high bulk density and low plant-available

P and exchangeable K in the soil.

The inclusion of an aerobic soil phase by growing an upland crop has been shown to

obtain substantial yields of crops that tend to have a much higher market value than rice.

The application of the organic substrates not only stimulated the performance of these

high-value crops, but may also result in significant residual effects on the subsequent

crop of wet season rice (Becker and Ladha, 1997; Eghball et al., 2004). Such

longer-term effects of substrate application on soil parameters may include enhanced

soil P dynamics, increasing availability of P, Mg, Zn, Fe, and Cu, as well as improving

soil biological and chemical properties (Kirk, 2004, pp. 135-164). It may thus be

assumed that the effects of substrate application reported in this paper are likely to

contribute to longer-term improvements of these production systems. While presenting

a promising option, the organic substrates need to be matched with soil-specific needs.

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Tropentag 2008

International Research on Food Security,Natural Resource Management and Rural Development

Competition for Resources in a Changing World:

New Drive for Rural Development

University of Hohenheim

October 7 - 9, 2008 in Stuttgart-Hohenheim

General information

The annual Conference on Tropical and Subtropical Agricultural and Natural Resource

Management (TROPENTAG) is jointly organised by the universities of Bonn, Gottin-

gen, Hohenheim, Kassel-Witzenhausen, Hamburg (2009), Zurich (2010) as well as by

the Council for Tropical and Subtropical Research (ATSAF e.V.) in co-operation with

the GTZ Advisory Service on Agricultural Research for Development (BEAF).

Tropentag 2008 will be held in Hohenheim. All students, Ph.D. students, scientists, ex-

tensionists, decision makers, politicians and practical farmers, interested and engaged in

Agricultural Research and Rural Development in the Tropics and Subtropics are invited

to participate and to contribute.

Target of the conference

The Tropentag is a development-oriented and interdisciplinary conference. It addresses

issues of resource-, environmental-, agricultural-, forestry-, fisheries-, food-, nutrition

and related sciences in the context of international rural development, sustainable re-

source use and poverty alleviation worldwide.

Plenary session

The growing demand for food for a still rapidly increasing population in the South, an

alarming decrease in available arable land, increasing impact of climate change and the

emergence of bioenergy production as a new powerful and competitive player enhance

the competition for resources in a changing World.

Invited international speakers will present their view on these recent trends and analyse

who will actually benefit from the new drive for rural development.

Eiselen award plenary session

On the occasion of this conference a special plenary session will be devoted to the pre-

sentation of the “Hans H. Ruthenberg-Graduate-Award” and the “Josef G. Knoll

European Science Award 2008” by the “Eiselen Foundation”, Ulm.

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Oral and poster presentations

The Tropentag 2008 entitled “Competition for Resources in a Changing World - New

Drive for Rural Development” particularly welcomes contributions pertaining to rural

development, hunger and poverty alleviation, climate change issues, the conflicting field

of food vs. bioenergy production, and their environmental repercussions and influences

of globalisation on these topics. The Tropentag will be organised in four sessions of five

parallel thematic groups. Each session will be opened by an invited keynote lecture, to

be followed by four original papers.

Posters contributing to the different topics will be introduced during a plenary session on

the first day at early evening time. On the second day there will be two parallel guided

poster sessions around lunch time.

Local organising committee

• Prof. Dr. Georg Cadisch

• Prof. Dr. Folkard Asch

• Dr. Ludwig Kammesheidt

• Barbel Sagi, MSc

Further Information:

http://www.tropentag.de

e-mail: [email protected]

110


formerly: Der Tropenlandwirt / Beitrage zur tropischen Landwirtschaft und Veterinarme-

dizin

Notes to authors

The Journal of Agriculture in the Tropics and Subtropics publishes papers and short

communications dealing with original research in the fields of rural economy and farm

management, plant production, soil science, animal nutrition and animal husbandry, ve-

terinary hygiene and protection against epidemics, forestry and forest economy.

The sole responsibility for the contents rests with the author. The papers must not

have been submitted elsewhere for publication. If accepted, they may not be published

elsewhere without the permission of the editors.

Manuscripts are accepted in German, English, French, and Spanish. Papers may not be

published in the order of receipt, those that require minor amendments, only are likely

to appear earlier. Authors are advised to retain one copy of the manuscript themselves

as the editors cannot accept any responsibility for damage or loss of manuscripts.

1. Contents of the manuscripts

Findings should be presented as brief as possible. Publication of a paper in consecutive

parts will be considered in exceptional cases.

The following set-up is recommended:

The introduction should be as brief as possible and should concentrate on the main

topics of the paper. Reference should be made to recent and important literature on the

subject, only.

Materials used and methods applied should be explained briefly. Well-known or esta-

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first name of the author(s), title of the paper, name of the journal, number of the vo-

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On publication, each author will receive two copy of the Journal

Manuscripts and communication should be addressed to:

Journal of Agriculture and Rural Development in the Tropics and Subtropics, formerly

Der Tropenlandwirt/Beitrage zur tropischen Landwirtschaft und Veterinarmedizin

Editorial Board

Steinstrasse 19,D-37213 Witzenhausen

E-mail: [email protected] , Fax (0) 5542 981313

April 2007

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